diff --git a/libsolidity/ArrayUtils.cpp b/libsolidity/ArrayUtils.cpp
index a064b2f57..2596e4afa 100644
--- a/libsolidity/ArrayUtils.cpp
+++ b/libsolidity/ArrayUtils.cpp
@@ -34,8 +34,10 @@ using namespace solidity;
 
 void ArrayUtils::copyArrayToStorage(ArrayType const& _targetType, ArrayType const& _sourceType) const
 {
-	// stack layout: [source_ref] target_ref (top)
-	// need to leave target_ref on the stack at the end
+	// this copies source to target and also clears target if it was larger
+	// need to leave "target_ref target_byte_off" on the stack at the end
+
+	// stack layout: [source_ref] [source_byte_off] [source length] target_ref target_byte_off (top)
 	solAssert(_targetType.getLocation() == ArrayType::Location::Storage, "");
 	solAssert(
 		_sourceType.getLocation() == ArrayType::Location::CallData ||
@@ -47,14 +49,20 @@ void ArrayUtils::copyArrayToStorage(ArrayType const& _targetType, ArrayType cons
 	Type const* targetBaseType = _targetType.isByteArray() ? &uint256 : &(*_targetType.getBaseType());
 	Type const* sourceBaseType = _sourceType.isByteArray() ? &uint256 : &(*_sourceType.getBaseType());
 
-	// this copies source to target and also clears target if it was larger
-
 	// TODO unroll loop for small sizes
 
-	// stack: source_ref [source_length] target_ref
+	bool sourceIsStorage = _sourceType.getLocation() == ArrayType::Location::Storage;
+
+	// stack: source_ref [source_byte_off] [source_length] target_ref target_byte_off
 	// store target_ref
+	m_context << eth::Instruction::POP; //@todo
 	for (unsigned i = _sourceType.getSizeOnStack(); i > 0; --i)
 		m_context << eth::swapInstruction(i);
+	// stack: target_ref source_ref [source_byte_off] [source_length]
+	if (sourceIsStorage)
+		m_context << eth::Instruction::POP; //@todo
+	// stack: target_ref source_ref [source_length]
+	// retrieve source length
 	if (_sourceType.getLocation() != ArrayType::Location::CallData || !_sourceType.isDynamicallySized())
 		retrieveLength(_sourceType); // otherwise, length is already there
 	// stack: target_ref source_ref source_length
@@ -73,6 +81,7 @@ void ArrayUtils::copyArrayToStorage(ArrayType const& _targetType, ArrayType cons
 		m_context
 			<< eth::Instruction::POP << eth::Instruction::POP
 			<< eth::Instruction::POP << eth::Instruction::POP;
+		m_context << u256(0); //@todo
 		return;
 	}
 	// compute hashes (data positions)
@@ -109,32 +118,37 @@ void ArrayUtils::copyArrayToStorage(ArrayType const& _targetType, ArrayType cons
 	// copy
 	if (sourceBaseType->getCategory() == Type::Category::Array)
 	{
-		m_context << eth::Instruction::DUP3 << eth::Instruction::DUP3;
+		//@todo
+		m_context << eth::Instruction::DUP3;
+		if (sourceIsStorage)
+			m_context << u256(0);
+		m_context << eth::dupInstruction(sourceIsStorage ? 4 : 3) << u256(0);
 		copyArrayToStorage(
 			dynamic_cast<ArrayType const&>(*targetBaseType),
 			dynamic_cast<ArrayType const&>(*sourceBaseType)
 		);
-		m_context << eth::Instruction::POP;
+		m_context << eth::Instruction::POP << eth::Instruction::POP;
 	}
 	else
 	{
 		m_context << eth::Instruction::DUP3;
 		if (_sourceType.getLocation() == ArrayType::Location::Storage)
+		{
+			m_context << u256(0);
 			StorageItem(m_context, *sourceBaseType).retrieveValue(SourceLocation(), true);
+		}
 		else if (sourceBaseType->isValueType())
 			CompilerUtils(m_context).loadFromMemoryDynamic(*sourceBaseType, true, true, false);
 		else
 			solAssert(false, "Copying of unknown type requested: " + sourceBaseType->toString());
 		solAssert(2 + sourceBaseType->getSizeOnStack() <= 16, "Stack too deep.");
-		m_context << eth::dupInstruction(2 + sourceBaseType->getSizeOnStack());
+		m_context << eth::dupInstruction(2 + sourceBaseType->getSizeOnStack()) << u256(0);
 		StorageItem(m_context, *targetBaseType).storeValue(*sourceBaseType, SourceLocation(), true);
 	}
 	// increment source
 	m_context
 		<< eth::Instruction::SWAP2
-		<< (_sourceType.getLocation() == ArrayType::Location::Storage ?
-			sourceBaseType->getStorageSize() :
-			sourceBaseType->getCalldataEncodedSize())
+		<< (sourceIsStorage ? sourceBaseType->getStorageSize() : sourceBaseType->getCalldataEncodedSize())
 		<< eth::Instruction::ADD
 		<< eth::Instruction::SWAP2;
 	// increment target
@@ -147,40 +161,48 @@ void ArrayUtils::copyArrayToStorage(ArrayType const& _targetType, ArrayType cons
 	m_context << copyLoopEnd;
 
 	// zero-out leftovers in target
-	// stack: target_ref target_data_end source_data_pos target_data_pos source_data_end
+	// stack: target_ref target_data_end source_data_pos target_data_pos_updated source_data_end
 	m_context << eth::Instruction::POP << eth::Instruction::SWAP1 << eth::Instruction::POP;
 	// stack: target_ref target_data_end target_data_pos_updated
 	clearStorageLoop(*targetBaseType);
 	m_context << eth::Instruction::POP;
+	m_context << u256(0); //@todo
 }
 
 void ArrayUtils::clearArray(ArrayType const& _type) const
 {
+	unsigned stackHeightStart = m_context.getStackHeight();
 	solAssert(_type.getLocation() == ArrayType::Location::Storage, "");
 	if (_type.isDynamicallySized())
+	{
+		m_context << eth::Instruction::POP; // remove byte offset
 		clearDynamicArray(_type);
+	}
 	else if (_type.getLength() == 0 || _type.getBaseType()->getCategory() == Type::Category::Mapping)
-		m_context << eth::Instruction::POP;
+		m_context << eth::Instruction::POP << eth::Instruction::POP;
 	else if (_type.getLength() < 5) // unroll loop for small arrays @todo choose a good value
 	{
 		solAssert(!_type.isByteArray(), "");
 		for (unsigned i = 1; i < _type.getLength(); ++i)
 		{
 			StorageItem(m_context, *_type.getBaseType()).setToZero(SourceLocation(), false);
+			m_context << eth::Instruction::SWAP1;
 			m_context << u256(_type.getBaseType()->getStorageSize()) << eth::Instruction::ADD;
+			m_context << eth::Instruction::SWAP1;
 		}
 		StorageItem(m_context, *_type.getBaseType()).setToZero(SourceLocation(), true);
 	}
 	else
 	{
 		solAssert(!_type.isByteArray(), "");
-		m_context
-			<< eth::Instruction::DUP1 << u256(_type.getLength())
-			<< u256(_type.getBaseType()->getStorageSize())
-			<< eth::Instruction::MUL << eth::Instruction::ADD << eth::Instruction::SWAP1;
+		m_context << eth::Instruction::SWAP1;
+		m_context << eth::Instruction::DUP1 << _type.getLength();
+		convertLengthToSize(_type);
+		m_context << eth::Instruction::ADD << eth::Instruction::SWAP1;
 		clearStorageLoop(*_type.getBaseType());
-		m_context << eth::Instruction::POP;
+		m_context << eth::Instruction::POP << eth::Instruction::POP;
 	}
+	solAssert(m_context.getStackHeight() == stackHeightStart - 2, "");
 }
 
 void ArrayUtils::clearDynamicArray(ArrayType const& _type) const
@@ -188,6 +210,7 @@ void ArrayUtils::clearDynamicArray(ArrayType const& _type) const
 	solAssert(_type.getLocation() == ArrayType::Location::Storage, "");
 	solAssert(_type.isDynamicallySized(), "");
 
+	unsigned stackHeightStart = m_context.getStackHeight();
 	// fetch length
 	m_context << eth::Instruction::DUP1 << eth::Instruction::SLOAD;
 	// set length to zero
@@ -197,7 +220,7 @@ void ArrayUtils::clearDynamicArray(ArrayType const& _type) const
 	// compute data positions
 	m_context << eth::Instruction::SWAP1;
 	CompilerUtils(m_context).computeHashStatic();
-	// stack: len data_pos (len is in slots for byte array and in items for other arrays)
+	// stack: len data_pos
 	m_context << eth::Instruction::SWAP1 << eth::Instruction::DUP2 << eth::Instruction::ADD
 		<< eth::Instruction::SWAP1;
 	// stack: data_pos_end data_pos
@@ -207,6 +230,7 @@ void ArrayUtils::clearDynamicArray(ArrayType const& _type) const
 		clearStorageLoop(*_type.getBaseType());
 	// cleanup
 	m_context << eth::Instruction::POP;
+	solAssert(m_context.getStackHeight() == stackHeightStart - 1, "");
 }
 
 void ArrayUtils::resizeDynamicArray(const ArrayType& _type) const
@@ -214,6 +238,7 @@ void ArrayUtils::resizeDynamicArray(const ArrayType& _type) const
 	solAssert(_type.getLocation() == ArrayType::Location::Storage, "");
 	solAssert(_type.isDynamicallySized(), "");
 
+	unsigned stackHeightStart = m_context.getStackHeight();
 	eth::AssemblyItem resizeEnd = m_context.newTag();
 
 	// stack: ref new_length
@@ -249,10 +274,12 @@ void ArrayUtils::resizeDynamicArray(const ArrayType& _type) const
 	m_context << resizeEnd;
 	// cleanup
 	m_context << eth::Instruction::POP << eth::Instruction::POP << eth::Instruction::POP;
+	solAssert(m_context.getStackHeight() == stackHeightStart - 2, "");
 }
 
 void ArrayUtils::clearStorageLoop(Type const& _type) const
 {
+	unsigned stackHeightStart = m_context.getStackHeight();
 	if (_type.getCategory() == Type::Category::Mapping)
 	{
 		m_context << eth::Instruction::POP;
@@ -267,13 +294,16 @@ void ArrayUtils::clearStorageLoop(Type const& _type) const
 	eth::AssemblyItem zeroLoopEnd = m_context.newTag();
 	m_context.appendConditionalJumpTo(zeroLoopEnd);
 	// delete
+	m_context << u256(0); //@todo
 	StorageItem(m_context, _type).setToZero(SourceLocation(), false);
+	m_context << eth::Instruction::POP;
 	// increment
 	m_context << u256(1) << eth::Instruction::ADD;
 	m_context.appendJumpTo(loopStart);
 	// cleanup
 	m_context << zeroLoopEnd;
 	m_context << eth::Instruction::POP;
+	solAssert(m_context.getStackHeight() == stackHeightStart - 1, "");
 }
 
 void ArrayUtils::convertLengthToSize(ArrayType const& _arrayType, bool _pad) const
diff --git a/libsolidity/ArrayUtils.h b/libsolidity/ArrayUtils.h
index 31cca8173..c7b05b6d3 100644
--- a/libsolidity/ArrayUtils.h
+++ b/libsolidity/ArrayUtils.h
@@ -41,19 +41,19 @@ public:
 
 	/// Copies an array to an array in storage. The arrays can be of different types only if
 	/// their storage representation is the same.
-	/// Stack pre: [source_reference] target_reference
-	/// Stack post: target_reference
+	/// Stack pre: source_reference [source_byte_offset/source_length] target_reference target_byte_offset
+	/// Stack post: target_reference target_byte_offset
 	void copyArrayToStorage(ArrayType const& _targetType, ArrayType const& _sourceType) const;
 	/// Clears the given dynamic or static array.
-	/// Stack pre: reference
+	/// Stack pre: storage_ref storage_byte_offset
 	/// Stack post:
 	void clearArray(ArrayType const& _type) const;
 	/// Clears the length and data elements of the array referenced on the stack.
-	/// Stack pre: reference
+	/// Stack pre: reference (excludes byte offset)
 	/// Stack post:
 	void clearDynamicArray(ArrayType const& _type) const;
 	/// Changes the size of a dynamic array and clears the tail if it is shortened.
-	/// Stack pre: reference new_length
+	/// Stack pre: reference (excludes byte offset) new_length
 	/// Stack post:
 	void resizeDynamicArray(ArrayType const& _type) const;
 	/// Appends a loop that clears a sequence of storage slots of the given type (excluding end).
@@ -67,7 +67,7 @@ public:
 	void convertLengthToSize(ArrayType const& _arrayType, bool _pad = false) const;
 	/// Retrieves the length (number of elements) of the array ref on the stack. This also
 	/// works for statically-sized arrays.
-	/// Stack pre: reference
+	/// Stack pre: reference (excludes byte offset for dynamic storage arrays)
 	/// Stack post: reference length
 	void retrieveLength(ArrayType const& _arrayType) const;
 
diff --git a/libsolidity/Compiler.cpp b/libsolidity/Compiler.cpp
index 0f4e89de1..db61cc4a1 100644
--- a/libsolidity/Compiler.cpp
+++ b/libsolidity/Compiler.cpp
@@ -274,10 +274,19 @@ void Compiler::appendReturnValuePacker(TypePointers const& _typeParameters)
 
 void Compiler::registerStateVariables(ContractDefinition const& _contract)
 {
+	vector<VariableDeclaration const*> variables;
 	for (ContractDefinition const* contract: boost::adaptors::reverse(_contract.getLinearizedBaseContracts()))
 		for (ASTPointer<VariableDeclaration> const& variable: contract->getStateVariables())
 			if (!variable->isConstant())
-				m_context.addStateVariable(*variable);
+				variables.push_back(variable.get());
+	TypePointers types;
+	for (auto variable: variables)
+		types.push_back(variable->getType());
+	StorageOffsets offsets;
+	offsets.computeOffsets(types);
+	for (size_t index = 0; index < variables.size(); ++index)
+		if (auto const* offset = offsets.getOffset(index))
+			m_context.addStateVariable(*variables[index], offset->first, offset->second);
 }
 
 void Compiler::initializeStateVariables(ContractDefinition const& _contract)
diff --git a/libsolidity/CompilerContext.cpp b/libsolidity/CompilerContext.cpp
index f2bb1de20..7cade367c 100644
--- a/libsolidity/CompilerContext.cpp
+++ b/libsolidity/CompilerContext.cpp
@@ -37,15 +37,13 @@ void CompilerContext::addMagicGlobal(MagicVariableDeclaration const& _declaratio
 	m_magicGlobals.insert(&_declaration);
 }
 
-void CompilerContext::addStateVariable(VariableDeclaration const& _declaration)
+void CompilerContext::addStateVariable(
+	VariableDeclaration const& _declaration,
+	u256 const& _storageOffset,
+	unsigned _byteOffset
+)
 {
-	m_stateVariables[&_declaration] = m_stateVariablesSize;
-	bigint newSize = bigint(m_stateVariablesSize) + _declaration.getType()->getStorageSize();
-	if (newSize >= bigint(1) << 256)
-		BOOST_THROW_EXCEPTION(TypeError()
-			<< errinfo_comment("State variable does not fit in storage.")
-			<< errinfo_sourceLocation(_declaration.getLocation()));
-	m_stateVariablesSize = u256(newSize);
+	m_stateVariables[&_declaration] = make_pair(_storageOffset, _byteOffset);
 }
 
 void CompilerContext::startFunction(Declaration const& _function)
@@ -170,7 +168,7 @@ unsigned CompilerContext::currentToBaseStackOffset(unsigned _offset) const
 	return m_asm.deposit() - _offset - 1;
 }
 
-u256 CompilerContext::getStorageLocationOfVariable(const Declaration& _declaration) const
+pair<u256, unsigned> CompilerContext::getStorageLocationOfVariable(const Declaration& _declaration) const
 {
 	auto it = m_stateVariables.find(&_declaration);
 	solAssert(it != m_stateVariables.end(), "Variable not found in storage.");
diff --git a/libsolidity/CompilerContext.h b/libsolidity/CompilerContext.h
index 76923a77a..87f90d4c4 100644
--- a/libsolidity/CompilerContext.h
+++ b/libsolidity/CompilerContext.h
@@ -24,6 +24,7 @@
 
 #include <ostream>
 #include <stack>
+#include <utility>
 #include <libevmcore/Instruction.h>
 #include <libevmcore/Assembly.h>
 #include <libsolidity/ASTForward.h>
@@ -42,7 +43,7 @@ class CompilerContext
 {
 public:
 	void addMagicGlobal(MagicVariableDeclaration const& _declaration);
-	void addStateVariable(VariableDeclaration const& _declaration);
+	void addStateVariable(VariableDeclaration const& _declaration, u256 const& _storageOffset, unsigned _byteOffset);
 	void addVariable(VariableDeclaration const& _declaration, unsigned _offsetToCurrent = 0);
 	void removeVariable(VariableDeclaration const& _declaration);
 	void addAndInitializeVariable(VariableDeclaration const& _declaration);
@@ -82,7 +83,7 @@ public:
 	/// Converts an offset relative to the current stack height to a value that can be used later
 	/// with baseToCurrentStackOffset to point to the same stack element.
 	unsigned currentToBaseStackOffset(unsigned _offset) const;
-	u256 getStorageLocationOfVariable(Declaration const& _declaration) const;
+	std::pair<u256, unsigned> getStorageLocationOfVariable(Declaration const& _declaration) const;
 
 	/// Appends a JUMPI instruction to a new tag and @returns the tag
 	eth::AssemblyItem appendConditionalJump() { return m_asm.appendJumpI().tag(); }
@@ -144,10 +145,8 @@ private:
 	std::set<Declaration const*> m_magicGlobals;
 	/// Other already compiled contracts to be used in contract creation calls.
 	std::map<ContractDefinition const*, bytes const*> m_compiledContracts;
-	/// Size of the state variables, offset of next variable to be added.
-	u256 m_stateVariablesSize = 0;
 	/// Storage offsets of state variables
-	std::map<Declaration const*, u256> m_stateVariables;
+	std::map<Declaration const*, std::pair<u256, unsigned>> m_stateVariables;
 	/// Offsets of local variables on the stack (relative to stack base).
 	std::map<Declaration const*, unsigned> m_localVariables;
 	/// Labels pointing to the entry points of functions.
diff --git a/libsolidity/CompilerUtils.cpp b/libsolidity/CompilerUtils.cpp
index e517e384d..511254fa5 100644
--- a/libsolidity/CompilerUtils.cpp
+++ b/libsolidity/CompilerUtils.cpp
@@ -93,6 +93,7 @@ void CompilerUtils::storeInMemoryDynamic(Type const& _type, bool _padToWordBound
 		else
 		{
 			solAssert(type.getLocation() == ArrayType::Location::Storage, "Memory arrays not yet implemented.");
+			m_context << eth::Instruction::POP; //@todo
 			m_context << eth::Instruction::DUP1 << eth::Instruction::SLOAD;
 			// stack here: memory_offset storage_offset length_bytes
 			// jump to end if length is zero
@@ -198,7 +199,6 @@ unsigned CompilerUtils::loadFromMemoryHelper(Type const& _type, bool _fromCallda
 	return numBytes;
 }
 
-
 unsigned CompilerUtils::prepareMemoryStore(Type const& _type, bool _padToWordBoundaries) const
 {
 	unsigned numBytes = _type.getCalldataEncodedSize(_padToWordBoundaries);
diff --git a/libsolidity/ExpressionCompiler.cpp b/libsolidity/ExpressionCompiler.cpp
index 92fd70437..a0a688bbd 100644
--- a/libsolidity/ExpressionCompiler.cpp
+++ b/libsolidity/ExpressionCompiler.cpp
@@ -67,9 +67,10 @@ void ExpressionCompiler::appendStateVariableAccessor(VariableDeclaration const&
 		length += CompilerUtils(m_context).storeInMemory(length, *paramType, true);
 
 	// retrieve the position of the variable
-	m_context << m_context.getStorageLocationOfVariable(_varDecl);
-	TypePointer returnType = _varDecl.getType();
+	auto const& location = m_context.getStorageLocationOfVariable(_varDecl);
+	m_context << location.first;
 
+	TypePointer returnType = _varDecl.getType();
 	for (TypePointer const& paramType: paramTypes)
 	{
 		// move offset to memory
@@ -90,9 +91,10 @@ void ExpressionCompiler::appendStateVariableAccessor(VariableDeclaration const&
 		// struct
 		for (size_t i = 0; i < names.size(); ++i)
 		{
-			m_context << eth::Instruction::DUP1
-					  << structType->getStorageOffsetOfMember(names[i])
-					  << eth::Instruction::ADD;
+			if (types[i]->getCategory() == Type::Category::Mapping)
+				continue;
+			pair<u256, unsigned> const& offsets = structType->getStorageOffsetsOfMember(names[i]);
+			m_context << eth::Instruction::DUP1 << u256(offsets.first) << eth::Instruction::ADD << u256(offsets.second);
 			StorageItem(m_context, *types[i]).retrieveValue(SourceLocation(), true);
 			solAssert(types[i]->getSizeOnStack() == 1, "Returning struct elements with stack size != 1 not yet implemented.");
 			m_context << eth::Instruction::SWAP1;
@@ -104,6 +106,7 @@ void ExpressionCompiler::appendStateVariableAccessor(VariableDeclaration const&
 	{
 		// simple value
 		solAssert(accessorType.getReturnParameterTypes().size() == 1, "");
+		m_context << u256(location.second);
 		StorageItem(m_context, *returnType).retrieveValue(SourceLocation(), true);
 		retSizeOnStack = returnType->getSizeOnStack();
 	}
@@ -280,23 +283,24 @@ bool ExpressionCompiler::visit(UnaryOperation const& _unaryOperation)
 	case Token::Dec: // -- (pre- or postfix)
 		solAssert(!!m_currentLValue, "LValue not retrieved.");
 		m_currentLValue->retrieveValue(_unaryOperation.getLocation());
-		solAssert(m_currentLValue->sizeOnStack() <= 1, "Not implemented.");
 		if (!_unaryOperation.isPrefixOperation())
 		{
-			if (m_currentLValue->sizeOnStack() == 1)
-				m_context << eth::Instruction::SWAP1 << eth::Instruction::DUP2;
-			else
-				m_context << eth::Instruction::DUP1;
+			// store value for later
+			solAssert(_unaryOperation.getType()->getSizeOnStack() == 1, "Stack size != 1 not implemented.");
+			m_context << eth::Instruction::DUP1;
+			if (m_currentLValue->sizeOnStack() > 0)
+				for (unsigned i = 1 + m_currentLValue->sizeOnStack(); i > 0; --i)
+					m_context << eth::swapInstruction(i);
 		}
 		m_context << u256(1);
 		if (_unaryOperation.getOperator() == Token::Inc)
 			m_context << eth::Instruction::ADD;
 		else
-			m_context << eth::Instruction::SWAP1 << eth::Instruction::SUB; // @todo avoid the swap
-		// Stack for prefix: [ref] (*ref)+-1
-		// Stack for postfix: *ref [ref] (*ref)+-1
-		if (m_currentLValue->sizeOnStack() == 1)
-			m_context << eth::Instruction::SWAP1;
+			m_context << eth::Instruction::SWAP1 << eth::Instruction::SUB;
+		// Stack for prefix: [ref...] (*ref)+-1
+		// Stack for postfix: *ref [ref...] (*ref)+-1
+		for (unsigned i = m_currentLValue->sizeOnStack(); i > 0; --i)
+			m_context << eth::swapInstruction(i);
 		m_currentLValue->storeValue(
 			*_unaryOperation.getType(), _unaryOperation.getLocation(),
 			!_unaryOperation.isPrefixOperation());
@@ -661,7 +665,9 @@ void ExpressionCompiler::endVisit(MemberAccess const& _memberAccess)
 	case Type::Category::Struct:
 	{
 		StructType const& type = dynamic_cast<StructType const&>(*_memberAccess.getExpression().getType());
-		m_context << type.getStorageOffsetOfMember(member) << eth::Instruction::ADD;
+		m_context << eth::Instruction::POP; // structs always align to new slot
+		pair<u256, unsigned> const& offsets = type.getStorageOffsetsOfMember(member);
+		m_context << offsets.first << eth::Instruction::ADD << u256(offsets.second);
 		setLValueToStorageItem(_memberAccess);
 		break;
 	}
@@ -729,20 +735,22 @@ bool ExpressionCompiler::visit(IndexAccess const& _indexAccess)
 	Type const& baseType = *_indexAccess.getBaseExpression().getType();
 	if (baseType.getCategory() == Type::Category::Mapping)
 	{
+		// storage byte offset is ignored for mappings, it should be zero.
+		m_context << eth::Instruction::POP;
+		// stack: storage_base_ref
 		Type const& keyType = *dynamic_cast<MappingType const&>(baseType).getKeyType();
-		m_context << u256(0);
+		m_context << u256(0); // memory position
 		solAssert(_indexAccess.getIndexExpression(), "Index expression expected.");
 		appendExpressionCopyToMemory(keyType, *_indexAccess.getIndexExpression());
-		solAssert(baseType.getSizeOnStack() == 1,
-				  "Unexpected: Not exactly one stack slot taken by subscriptable expression.");
 		m_context << eth::Instruction::SWAP1;
 		appendTypeMoveToMemory(IntegerType(256));
 		m_context << u256(0) << eth::Instruction::SHA3;
+		m_context << u256(0);
 		setLValueToStorageItem( _indexAccess);
 	}
 	else if (baseType.getCategory() == Type::Category::Array)
 	{
-		// stack layout: <base_ref> [<length>] <index>
+		// stack layout: <base_ref> [storage_byte_offset] [<length>] <index>
 		ArrayType const& arrayType = dynamic_cast<ArrayType const&>(baseType);
 		solAssert(_indexAccess.getIndexExpression(), "Index expression expected.");
 		ArrayType::Location location = arrayType.getLocation();
@@ -758,9 +766,11 @@ bool ExpressionCompiler::visit(IndexAccess const& _indexAccess)
 		else if (location == ArrayType::Location::CallData)
 			// length is stored on the stack
 			m_context << eth::Instruction::SWAP1;
+		else if (location == ArrayType::Location::Storage)
+			m_context << eth::Instruction::DUP3 << load;
 		else
 			m_context << eth::Instruction::DUP2 << load;
-		// stack: <base_ref> <index> <length>
+		// stack: <base_ref> [storage_byte_offset] <index> <length>
 		// check out-of-bounds access
 		m_context << eth::Instruction::DUP2 << eth::Instruction::LT;
 		eth::AssemblyItem legalAccess = m_context.appendConditionalJump();
@@ -768,7 +778,7 @@ bool ExpressionCompiler::visit(IndexAccess const& _indexAccess)
 		m_context << eth::Instruction::STOP;
 
 		m_context << legalAccess;
-		// stack: <base_ref> <index>
+		// stack: <base_ref> [storage_byte_offset] <index>
 		if (arrayType.isByteArray())
 			// byte array is packed differently, especially in storage
 			switch (location)
@@ -776,14 +786,15 @@ bool ExpressionCompiler::visit(IndexAccess const& _indexAccess)
 			case ArrayType::Location::Storage:
 				// byte array index storage lvalue on stack (goal):
 				// <ref> <byte_number> = <base_ref + index / 32> <index % 32>
-				m_context << u256(32) << eth::Instruction::SWAP2;
+				m_context << u256(32) << eth::Instruction::SWAP3;
 				CompilerUtils(m_context).computeHashStatic();
-				// stack: 32 index data_ref
+				// stack: 32 storage_byte_offset index data_ref
 				m_context
-					<< eth::Instruction::DUP3 << eth::Instruction::DUP3
+					<< eth::Instruction::DUP4 << eth::Instruction::DUP3
 					<< eth::Instruction::DIV << eth::Instruction::ADD
-				// stack: 32 index (data_ref + index / 32)
-					<< eth::Instruction::SWAP2 << eth::Instruction::SWAP1 << eth::Instruction::MOD;
+				// stack: 32 storage_byte_offset index (data_ref + index / 32)
+					<< eth::Instruction::SWAP3 << eth::Instruction::SWAP2
+					<< eth::Instruction::POP << eth::Instruction::MOD;
 				setLValue<StorageByteArrayElement>(_indexAccess);
 				break;
 			case ArrayType::Location::CallData:
@@ -797,6 +808,10 @@ bool ExpressionCompiler::visit(IndexAccess const& _indexAccess)
 			}
 		else
 		{
+			// stack: <base_ref> [storage_byte_offset] <index>
+			if (location == ArrayType::Location::Storage)
+				//@todo use byte offset, remove it for now
+				m_context << eth::Instruction::SWAP1 << eth::Instruction::POP;
 			u256 elementSize =
 				location == ArrayType::Location::Storage ?
 					arrayType.getBaseType()->getStorageSize() :
@@ -822,6 +837,7 @@ bool ExpressionCompiler::visit(IndexAccess const& _indexAccess)
 					CompilerUtils(m_context).loadFromMemoryDynamic(*arrayType.getBaseType(), true, true, false);
 				break;
 			case ArrayType::Location::Storage:
+				m_context << u256(0); // @todo
 				setLValueToStorageItem(_indexAccess);
 				break;
 			case ArrayType::Location::Memory:
@@ -1141,7 +1157,7 @@ void ExpressionCompiler::setLValueFromDeclaration(Declaration const& _declaratio
 	if (m_context.isLocalVariable(&_declaration))
 		setLValue<StackVariable>(_expression, _declaration);
 	else if (m_context.isStateVariable(&_declaration))
-			setLValue<StorageItem>(_expression, _declaration);
+		setLValue<StorageItem>(_expression, _declaration);
 	else
 		BOOST_THROW_EXCEPTION(InternalCompilerError()
 			<< errinfo_sourceLocation(_expression.getLocation())
diff --git a/libsolidity/ExpressionCompiler.h b/libsolidity/ExpressionCompiler.h
index 9cab757ea..e6caad747 100644
--- a/libsolidity/ExpressionCompiler.h
+++ b/libsolidity/ExpressionCompiler.h
@@ -140,7 +140,6 @@ void ExpressionCompiler::setLValue(Expression const& _expression, _Arguments con
 		m_currentLValue = move(lvalue);
 	else
 		lvalue->retrieveValue(_expression.getLocation(), true);
-
 }
 
 }
diff --git a/libsolidity/LValue.cpp b/libsolidity/LValue.cpp
index 68d6797eb..234072bce 100644
--- a/libsolidity/LValue.cpp
+++ b/libsolidity/LValue.cpp
@@ -77,7 +77,8 @@ void StackVariable::setToZero(SourceLocation const& _location, bool) const
 StorageItem::StorageItem(CompilerContext& _compilerContext, Declaration const& _declaration):
 	StorageItem(_compilerContext, *_declaration.getType())
 {
-	m_context << m_context.getStorageLocationOfVariable(_declaration);
+	auto const& location = m_context.getStorageLocationOfVariable(_declaration);
+	m_context << location.first << u256(location.second);
 }
 
 StorageItem::StorageItem(CompilerContext& _compilerContext, Type const& _type):
@@ -86,62 +87,78 @@ StorageItem::StorageItem(CompilerContext& _compilerContext, Type const& _type):
 	if (m_dataType.isValueType())
 	{
 		solAssert(m_dataType.getStorageSize() == m_dataType.getSizeOnStack(), "");
-		solAssert(m_dataType.getStorageSize() <= numeric_limits<unsigned>::max(),
-			"The storage size of " + m_dataType.toString() + " should fit in an unsigned");
-		m_size = unsigned(m_dataType.getStorageSize());
+		solAssert(m_dataType.getStorageSize() == 1, "Invalid storage size.");
 	}
-	else
-		m_size = 0; // unused
 }
 
 void StorageItem::retrieveValue(SourceLocation const&, bool _remove) const
 {
+	// stack: storage_key storage_offset
 	if (!m_dataType.isValueType())
 		return; // no distinction between value and reference for non-value types
 	if (!_remove)
-		m_context << eth::Instruction::DUP1;
-	if (m_size == 1)
-		m_context << eth::Instruction::SLOAD;
+		CompilerUtils(m_context).copyToStackTop(sizeOnStack(), sizeOnStack());
+	if (m_dataType.getStorageBytes() == 32)
+		m_context << eth::Instruction::POP << eth::Instruction::SLOAD;
 	else
-		for (unsigned i = 0; i < m_size; ++i)
-		{
-			m_context << eth::Instruction::DUP1 << eth::Instruction::SLOAD << eth::Instruction::SWAP1;
-			if (i + 1 < m_size)
-				m_context << u256(1) << eth::Instruction::ADD;
-			else
-				m_context << eth::Instruction::POP;
-		}
+	{
+		m_context
+			<< eth::Instruction::SWAP1 << eth::Instruction::SLOAD << eth::Instruction::SWAP1
+			<< u256(0x100) << eth::Instruction::EXP << eth::Instruction::SWAP1 << eth::Instruction::DIV;
+		if (m_dataType.getCategory() == Type::Category::FixedBytes)
+			m_context << (u256(0x1) << (256 - 8 * m_dataType.getStorageBytes())) << eth::Instruction::MUL;
+		else
+			m_context << ((u256(0x1) << (8 * m_dataType.getStorageBytes())) - 1) << eth::Instruction::AND;
+	}
 }
 
 void StorageItem::storeValue(Type const& _sourceType, SourceLocation const& _location, bool _move) const
 {
-	// stack layout: value value ... value target_ref
+	// stack: value storage_key storage_offset
 	if (m_dataType.isValueType())
 	{
-		if (!_move) // copy values
+		solAssert(m_dataType.getStorageBytes() <= 32, "Invalid storage bytes size.");
+		solAssert(m_dataType.getStorageBytes() > 0, "Invalid storage bytes size.");
+		if (m_dataType.getStorageBytes() == 32)
 		{
-			if (m_size + 1 > 16)
-				BOOST_THROW_EXCEPTION(CompilerError()
-					<< errinfo_sourceLocation(_location) << errinfo_comment("Stack too deep."));
-			for (unsigned i = 0; i < m_size; ++i)
-				m_context << eth::dupInstruction(m_size + 1) << eth::Instruction::SWAP1;
+			// offset should be zero
+			m_context << eth::Instruction::POP;
+			if (!_move)
+				m_context << eth::Instruction::DUP2 << eth::Instruction::SWAP1;
+			m_context << eth::Instruction::SSTORE;
 		}
-		if (m_size > 1) // store high index value first
-			m_context << u256(m_size - 1) << eth::Instruction::ADD;
-		for (unsigned i = 0; i < m_size; ++i)
+		else
 		{
-			if (i + 1 >= m_size)
-				m_context << eth::Instruction::SSTORE;
-			else
-				// stack here: value value ... value value (target_ref+offset)
-				m_context << eth::Instruction::SWAP1 << eth::Instruction::DUP2
-					<< eth::Instruction::SSTORE
-					<< u256(1) << eth::Instruction::SWAP1 << eth::Instruction::SUB;
+			// OR the value into the other values in the storage slot
+			m_context << u256(0x100) << eth::Instruction::EXP;
+			// stack: value storage_ref multiplier
+			// fetch old value
+			m_context << eth::Instruction::DUP2 << eth::Instruction::SLOAD;
+			// stack: value storege_ref multiplier old_full_value
+			// clear bytes in old value
+			m_context
+				<< eth::Instruction::DUP2 << ((u256(1) << (8 * m_dataType.getStorageBytes())) - 1)
+				<< eth::Instruction::MUL;
+			m_context << eth::Instruction::NOT << eth::Instruction::AND;
+			// stack: value storage_ref multiplier cleared_value
+			m_context
+				<< eth::Instruction::SWAP1 << eth::Instruction::DUP4;
+			// stack: value storage_ref cleared_value multiplier value
+			if (m_dataType.getCategory() == Type::Category::FixedBytes)
+				m_context
+					<< (u256(0x1) << (256 - 8 * dynamic_cast<FixedBytesType const&>(m_dataType).getNumBytes()))
+					<< eth::Instruction::SWAP1 << eth::Instruction::DIV;
+			m_context  << eth::Instruction::MUL << eth::Instruction::OR;
+			// stack: value storage_ref updated_value
+			m_context << eth::Instruction::SWAP1 << eth::Instruction::SSTORE;
+			if (_move)
+				m_context << eth::Instruction::POP;
 		}
 	}
 	else
 	{
-		solAssert(_sourceType.getCategory() == m_dataType.getCategory(),
+		solAssert(
+			_sourceType.getCategory() == m_dataType.getCategory(),
 			"Wrong type conversation for assignment.");
 		if (m_dataType.getCategory() == Type::Category::Array)
 		{
@@ -149,11 +166,12 @@ void StorageItem::storeValue(Type const& _sourceType, SourceLocation const& _loc
 						dynamic_cast<ArrayType const&>(m_dataType),
 						dynamic_cast<ArrayType const&>(_sourceType));
 			if (_move)
-				m_context << eth::Instruction::POP;
+				CompilerUtils(m_context).popStackElement(_sourceType);
 		}
 		else if (m_dataType.getCategory() == Type::Category::Struct)
 		{
-			// stack layout: source_ref target_ref
+			// stack layout: source_ref source_offset target_ref target_offset
+			// note that we have structs, so offsets should be zero and are ignored
 			auto const& structType = dynamic_cast<StructType const&>(m_dataType);
 			solAssert(structType == _sourceType, "Struct assignment with conversion.");
 			for (auto const& member: structType.getMembers())
@@ -162,27 +180,37 @@ void StorageItem::storeValue(Type const& _sourceType, SourceLocation const& _loc
 				TypePointer const& memberType = member.second;
 				if (memberType->getCategory() == Type::Category::Mapping)
 					continue;
-				m_context << structType.getStorageOffsetOfMember(member.first)
-					<< eth::Instruction::DUP3 << eth::Instruction::DUP2 << eth::Instruction::ADD;
-				// stack: source_ref target_ref member_offset source_member_ref
+				pair<u256, unsigned> const& offsets = structType.getStorageOffsetsOfMember(member.first);
+				m_context
+					<< offsets.first << u256(offsets.second)
+					<< eth::Instruction::DUP6 << eth::Instruction::DUP3
+					<< eth::Instruction::ADD << eth::Instruction::DUP2;
+				// stack: source_ref source_off target_ref target_off member_slot_offset member_byte_offset source_member_ref source_member_off
 				StorageItem(m_context, *memberType).retrieveValue(_location, true);
-				// stack: source_ref target_ref member_offset source_value...
-				solAssert(2 + memberType->getSizeOnStack() <= 16, "Stack too deep.");
-				m_context << eth::dupInstruction(2 + memberType->getSizeOnStack())
-					<< eth::dupInstruction(2 + memberType->getSizeOnStack()) << eth::Instruction::ADD;
-				// stack: source_ref target_ref member_offset source_value... target_member_ref
+				// stack: source_ref source_off target_ref target_off member_offset source_value...
+				solAssert(4 + memberType->getSizeOnStack() <= 16, "Stack too deep.");
+				m_context
+					<< eth::dupInstruction(4 + memberType->getSizeOnStack())
+					<< eth::dupInstruction(3 + memberType->getSizeOnStack()) << eth::Instruction::ADD
+					<< eth::dupInstruction(2 + memberType->getSizeOnStack());
+				// stack: source_ref source_off target_ref target_off member_slot_offset member_byte_offset source_value... target_member_ref target_member_byte_off
 				StorageItem(m_context, *memberType).storeValue(*memberType, _location, true);
-				m_context << eth::Instruction::POP;
+				m_context << eth::Instruction::POP << eth::Instruction::POP;
 			}
 			if (_move)
-				m_context << eth::Instruction::POP;
+				m_context
+					<< eth::Instruction::POP << eth::Instruction::POP
+					<< eth::Instruction::POP << eth::Instruction::POP;
 			else
-				m_context << eth::Instruction::SWAP1;
-			m_context << eth::Instruction::POP;
+				m_context
+					<< eth::Instruction::SWAP2 << eth::Instruction::POP
+					<< eth::Instruction::SWAP2 << eth::Instruction::POP;
 		}
 		else
-			BOOST_THROW_EXCEPTION(InternalCompilerError()
-				<< errinfo_sourceLocation(_location) << errinfo_comment("Invalid non-value type for assignment."));
+			BOOST_THROW_EXCEPTION(
+				InternalCompilerError()
+					<< errinfo_sourceLocation(_location)
+					<< errinfo_comment("Invalid non-value type for assignment."));
 	}
 }
 
@@ -191,12 +219,13 @@ void StorageItem::setToZero(SourceLocation const&, bool _removeReference) const
 	if (m_dataType.getCategory() == Type::Category::Array)
 	{
 		if (!_removeReference)
-			m_context << eth::Instruction::DUP1;
+			CompilerUtils(m_context).copyToStackTop(sizeOnStack(), sizeOnStack());
 		ArrayUtils(m_context).clearArray(dynamic_cast<ArrayType const&>(m_dataType));
 	}
 	else if (m_dataType.getCategory() == Type::Category::Struct)
 	{
-		// stack layout: ref
+		// stack layout: storage_key storage_offset
+		// @todo this can be improved for packed types
 		auto const& structType = dynamic_cast<StructType const&>(m_dataType);
 		for (auto const& member: structType.getMembers())
 		{
@@ -204,32 +233,42 @@ void StorageItem::setToZero(SourceLocation const&, bool _removeReference) const
 			TypePointer const& memberType = member.second;
 			if (memberType->getCategory() == Type::Category::Mapping)
 				continue;
-			m_context << structType.getStorageOffsetOfMember(member.first)
-				<< eth::Instruction::DUP2 << eth::Instruction::ADD;
+			pair<u256, unsigned> const& offsets = structType.getStorageOffsetsOfMember(member.first);
+			m_context
+				<< offsets.first << eth::Instruction::DUP3 << eth::Instruction::ADD
+				<< u256(offsets.second);
 			StorageItem(m_context, *memberType).setToZero();
 		}
 		if (_removeReference)
-			m_context << eth::Instruction::POP;
+			m_context << eth::Instruction::POP << eth::Instruction::POP;
 	}
 	else
 	{
 		solAssert(m_dataType.isValueType(), "Clearing of unsupported type requested: " + m_dataType.toString());
-		if (m_size == 0 && _removeReference)
-			m_context << eth::Instruction::POP;
-		else if (m_size == 1)
+		// @todo actually use offset
+		if (!_removeReference)
+			CompilerUtils(m_context).copyToStackTop(sizeOnStack(), sizeOnStack());
+		if (m_dataType.getStorageBytes() == 32)
+		{
+			// offset should be zero
 			m_context
-				<< u256(0) << (_removeReference ? eth::Instruction::SWAP1 : eth::Instruction::DUP2)
-				<< eth::Instruction::SSTORE;
+				<< eth::Instruction::POP << u256(0)
+				<< eth::Instruction::SWAP1 << eth::Instruction::SSTORE;
+		}
 		else
 		{
-			if (!_removeReference)
-				m_context << eth::Instruction::DUP1;
-			for (unsigned i = 0; i < m_size; ++i)
-				if (i + 1 >= m_size)
-					m_context << u256(0) << eth::Instruction::SWAP1 << eth::Instruction::SSTORE;
-				else
-					m_context << u256(0) << eth::Instruction::DUP2 << eth::Instruction::SSTORE
-						<< u256(1) << eth::Instruction::ADD;
+			m_context << u256(0x100) << eth::Instruction::EXP;
+			// stack: storage_ref multiplier
+			// fetch old value
+			m_context << eth::Instruction::DUP2 << eth::Instruction::SLOAD;
+			// stack: storege_ref multiplier old_full_value
+			// clear bytes in old value
+			m_context
+				<< eth::Instruction::SWAP1 << ((u256(1) << (8 * m_dataType.getStorageBytes())) - 1)
+				<< eth::Instruction::MUL;
+			m_context << eth::Instruction::NOT << eth::Instruction::AND;
+			// stack: storage_ref cleared_value
+			m_context << eth::Instruction::SWAP1 << eth::Instruction::SSTORE;
 		}
 	}
 }
@@ -300,6 +339,8 @@ StorageArrayLength::StorageArrayLength(CompilerContext& _compilerContext, const
 	m_arrayType(_arrayType)
 {
 	solAssert(m_arrayType.isDynamicallySized(), "");
+	// storage byte offset must be zero
+	m_context << eth::Instruction::POP;
 }
 
 void StorageArrayLength::retrieveValue(SourceLocation const&, bool _remove) const
diff --git a/libsolidity/LValue.h b/libsolidity/LValue.h
index c57c80e37..ad6225162 100644
--- a/libsolidity/LValue.h
+++ b/libsolidity/LValue.h
@@ -98,7 +98,9 @@ private:
 };
 
 /**
- * Reference to some item in storage. The (starting) position of the item is stored on the stack.
+ * Reference to some item in storage. On the stack this is <storage key> <offset_inside_value>,
+ * where 0 <= offset_inside_value < 32 and an offset of i means that the value is multiplied
+ * by 2**i before storing it.
  */
 class StorageItem: public LValue
 {
@@ -107,6 +109,7 @@ public:
 	StorageItem(CompilerContext& _compilerContext, Declaration const& _declaration);
 	/// Constructs the LValue and assumes that the storage reference is already on the stack.
 	StorageItem(CompilerContext& _compilerContext, Type const& _type);
+	virtual unsigned sizeOnStack() const { return 2; }
 	virtual void retrieveValue(SourceLocation const& _location, bool _remove = false) const override;
 	virtual void storeValue(
 		Type const& _sourceType,
@@ -117,11 +120,6 @@ public:
 		SourceLocation const& _location = SourceLocation(),
 		bool _removeReference = true
 	) const override;
-
-private:
-	/// Number of stack elements occupied by the value (not the reference).
-	/// Only used for value types.
-	unsigned m_size;
 };
 
 /**
diff --git a/libsolidity/Types.cpp b/libsolidity/Types.cpp
index 70cbec5d9..04f86b922 100644
--- a/libsolidity/Types.cpp
+++ b/libsolidity/Types.cpp
@@ -35,6 +35,81 @@ namespace dev
 namespace solidity
 {
 
+void StorageOffsets::computeOffsets(TypePointers const& _types)
+{
+	bigint slotOffset = 0;
+	unsigned byteOffset = 0;
+	map<size_t, pair<u256, unsigned>> offsets;
+	for (size_t i = 0; i < _types.size(); ++i)
+	{
+		TypePointer const& type = _types[i];
+		if (!type->canBeStored())
+			continue;
+		if (byteOffset + type->getStorageBytes() > 32)
+		{
+			// would overflow, go to next slot
+			++slotOffset;
+			byteOffset = 0;
+		}
+		if (slotOffset >= bigint(1) << 256)
+			BOOST_THROW_EXCEPTION(TypeError() << errinfo_comment("Object too large for storage."));
+		offsets[i] = make_pair(u256(slotOffset), byteOffset);
+		solAssert(type->getStorageSize() >= 1, "Invalid storage size.");
+		if (type->getStorageSize() == 1 && byteOffset + type->getStorageBytes() <= 32)
+			byteOffset += type->getStorageBytes();
+		else
+		{
+			slotOffset += type->getStorageSize();
+			byteOffset = 0;
+		}
+	}
+	if (byteOffset > 0)
+		++slotOffset;
+	if (slotOffset >= bigint(1) << 256)
+		BOOST_THROW_EXCEPTION(TypeError() << errinfo_comment("Object too large for storage."));
+	m_storageSize = u256(slotOffset);
+	swap(m_offsets, offsets);
+}
+
+pair<u256, unsigned> const* StorageOffsets::getOffset(size_t _index) const
+{
+	if (m_offsets.count(_index))
+		return &m_offsets.at(_index);
+	else
+		return nullptr;
+}
+
+MemberList& MemberList::operator=(MemberList&& _other)
+{
+	m_memberTypes = std::move(_other.m_memberTypes);
+	m_storageOffsets = std::move(_other.m_storageOffsets);
+	return *this;
+}
+
+std::pair<u256, unsigned> const* MemberList::getMemberStorageOffset(string const& _name) const
+{
+	if (!m_storageOffsets)
+	{
+		TypePointers memberTypes;
+		memberTypes.reserve(m_memberTypes.size());
+		for (auto const& nameAndType: m_memberTypes)
+			memberTypes.push_back(nameAndType.second);
+		m_storageOffsets.reset(new StorageOffsets());
+		m_storageOffsets->computeOffsets(memberTypes);
+	}
+	for (size_t index = 0; index < m_memberTypes.size(); ++index)
+		if (m_memberTypes[index].first == _name)
+			return m_storageOffsets->getOffset(index);
+	return nullptr;
+}
+
+u256 const& MemberList::getStorageSize() const
+{
+	// trigger lazy computation
+	getMemberStorageOffset("");
+	return m_storageOffsets->getStorageSize();
+}
+
 TypePointer Type::fromElementaryTypeName(Token::Value _typeToken)
 {
 	char const* tokenCstr = Token::toString(_typeToken);
@@ -149,7 +224,7 @@ TypePointer Type::commonType(TypePointer const& _a, TypePointer const& _b)
 		return TypePointer();
 }
 
-const MemberList Type::EmptyMemberList = MemberList();
+const MemberList Type::EmptyMemberList;
 
 IntegerType::IntegerType(int _bits, IntegerType::Modifier _modifier):
 	m_bits(_bits), m_modifier(_modifier)
@@ -235,10 +310,11 @@ TypePointer IntegerType::binaryOperatorResult(Token::Value _operator, TypePointe
 	return commonType;
 }
 
-const MemberList IntegerType::AddressMemberList =
-	MemberList({{"balance", make_shared<IntegerType >(256)},
-				{"call", make_shared<FunctionType>(strings(), strings(), FunctionType::Location::Bare, true)},
-				{"send", make_shared<FunctionType>(strings{"uint"}, strings{}, FunctionType::Location::Send)}});
+const MemberList IntegerType::AddressMemberList({
+	{"balance", make_shared<IntegerType >(256)},
+	{"call", make_shared<FunctionType>(strings(), strings(), FunctionType::Location::Bare, true)},
+	{"send", make_shared<FunctionType>(strings{"uint"}, strings{}, FunctionType::Location::Send)}
+});
 
 IntegerConstantType::IntegerConstantType(Literal const& _literal)
 {
@@ -644,6 +720,9 @@ unsigned ArrayType::getSizeOnStack() const
 	if (m_location == Location::CallData)
 		// offset [length] (stack top)
 		return 1 + (isDynamicallySized() ? 1 : 0);
+	else if (m_location == Location::Storage)
+		// storage_key storage_offset
+		return 2;
 	else
 		// offset
 		return 1;
@@ -672,7 +751,7 @@ shared_ptr<ArrayType> ArrayType::copyForLocation(ArrayType::Location _location)
 	return copy;
 }
 
-const MemberList ArrayType::s_arrayTypeMemberList = MemberList({{"length", make_shared<IntegerType>(256)}});
+const MemberList ArrayType::s_arrayTypeMemberList({{"length", make_shared<IntegerType>(256)}});
 
 bool ContractType::operator==(Type const& _other) const
 {
@@ -748,12 +827,7 @@ bool StructType::operator==(Type const& _other) const
 
 u256 StructType::getStorageSize() const
 {
-	bigint size = 0;
-	for (pair<string, TypePointer> const& member: getMembers())
-		size += member.second->getStorageSize();
-	if (size >= bigint(1) << 256)
-		BOOST_THROW_EXCEPTION(TypeError() << errinfo_comment("Struct too large for storage."));
-	return max<u256>(1, u256(size));
+	return max<u256>(1, getMembers().getStorageSize());
 }
 
 bool StructType::canLiveOutsideStorage() const
@@ -782,17 +856,11 @@ MemberList const& StructType::getMembers() const
 	return *m_members;
 }
 
-u256 StructType::getStorageOffsetOfMember(string const& _name) const
+pair<u256, unsigned> const& StructType::getStorageOffsetsOfMember(string const& _name) const
 {
-	//@todo cache member offset?
-	u256 offset;
-	for (ASTPointer<VariableDeclaration> const& variable: m_struct.getMembers())
-	{
-		if (variable->getName() == _name)
-			return offset;
-		offset += variable->getType()->getStorageSize();
-	}
-	BOOST_THROW_EXCEPTION(InternalCompilerError() << errinfo_comment("Storage offset of non-existing member requested."));
+	auto const* offsets = getMembers().getMemberStorageOffset(_name);
+	solAssert(offsets, "Storage offset of non-existing member requested.");
+	return *offsets;
 }
 
 TypePointer EnumType::unaryOperatorResult(Token::Value _operator) const
@@ -808,6 +876,15 @@ bool EnumType::operator==(Type const& _other) const
 	return other.m_enum == m_enum;
 }
 
+unsigned EnumType::getStorageBytes() const
+{
+	size_t elements = m_enum.getMembers().size();
+	if (elements <= 1)
+		return 1;
+	else
+		return dev::bytesRequired(elements - 1);
+}
+
 string EnumType::toString() const
 {
 	return string("enum ") + m_enum.getName();
@@ -952,6 +1029,13 @@ string FunctionType::toString() const
 	return name + ")";
 }
 
+u256 FunctionType::getStorageSize() const
+{
+	BOOST_THROW_EXCEPTION(
+		InternalCompilerError()
+			<< errinfo_comment("Storage size of non-storable function type requested."));
+}
+
 unsigned FunctionType::getSizeOnStack() const
 {
 	Location location = m_location;
@@ -1074,6 +1158,13 @@ string MappingType::toString() const
 	return "mapping(" + getKeyType()->toString() + " => " + getValueType()->toString() + ")";
 }
 
+u256 VoidType::getStorageSize() const
+{
+	BOOST_THROW_EXCEPTION(
+		InternalCompilerError()
+			<< errinfo_comment("Storage size of non-storable void type requested."));
+}
+
 bool TypeType::operator==(Type const& _other) const
 {
 	if (_other.getCategory() != getCategory())
@@ -1082,6 +1173,13 @@ bool TypeType::operator==(Type const& _other) const
 	return *getActualType() == *other.getActualType();
 }
 
+u256 TypeType::getStorageSize() const
+{
+	BOOST_THROW_EXCEPTION(
+		InternalCompilerError()
+			<< errinfo_comment("Storage size of non-storable type type requested."));
+}
+
 MemberList const& TypeType::getMembers() const
 {
 	// We need to lazy-initialize it because of recursive references.
@@ -1119,6 +1217,13 @@ ModifierType::ModifierType(const ModifierDefinition& _modifier)
 	swap(params, m_parameterTypes);
 }
 
+u256 ModifierType::getStorageSize() const
+{
+	BOOST_THROW_EXCEPTION(
+		InternalCompilerError()
+			<< errinfo_comment("Storage size of non-storable type type requested."));
+}
+
 bool ModifierType::operator==(Type const& _other) const
 {
 	if (_other.getCategory() != getCategory())
@@ -1149,23 +1254,29 @@ MagicType::MagicType(MagicType::Kind _kind):
 	switch (m_kind)
 	{
 	case Kind::Block:
-		m_members = MemberList({{"coinbase", make_shared<IntegerType>(0, IntegerType::Modifier::Address)},
-								{"timestamp", make_shared<IntegerType>(256)},
-								{"blockhash", make_shared<FunctionType>(strings{"uint"}, strings{"bytes32"}, FunctionType::Location::BlockHash)},
-								{"difficulty", make_shared<IntegerType>(256)},
-								{"number", make_shared<IntegerType>(256)},
-								{"gaslimit", make_shared<IntegerType>(256)}});
+		m_members = move(MemberList({
+			{"coinbase", make_shared<IntegerType>(0, IntegerType::Modifier::Address)},
+			{"timestamp", make_shared<IntegerType>(256)},
+			{"blockhash", make_shared<FunctionType>(strings{"uint"}, strings{"bytes32"}, FunctionType::Location::BlockHash)},
+			{"difficulty", make_shared<IntegerType>(256)},
+			{"number", make_shared<IntegerType>(256)},
+			{"gaslimit", make_shared<IntegerType>(256)}
+		}));
 		break;
 	case Kind::Message:
-		m_members = MemberList({{"sender", make_shared<IntegerType>(0, IntegerType::Modifier::Address)},
-								{"gas", make_shared<IntegerType>(256)},
-								{"value", make_shared<IntegerType>(256)},
-								{"data", make_shared<ArrayType>(ArrayType::Location::CallData)},
-								{"sig", make_shared<FixedBytesType>(4)}});
+		m_members = move(MemberList({
+			{"sender", make_shared<IntegerType>(0, IntegerType::Modifier::Address)},
+			{"gas", make_shared<IntegerType>(256)},
+			{"value", make_shared<IntegerType>(256)},
+			{"data", make_shared<ArrayType>(ArrayType::Location::CallData)},
+			{"sig", make_shared<FixedBytesType>(4)}
+		}));
 		break;
 	case Kind::Transaction:
-		m_members = MemberList({{"origin", make_shared<IntegerType>(0, IntegerType::Modifier::Address)},
-								{"gasprice", make_shared<IntegerType>(256)}});
+		m_members = move(MemberList({
+			{"origin", make_shared<IntegerType>(0, IntegerType::Modifier::Address)},
+			{"gasprice", make_shared<IntegerType>(256)}
+		}));
 		break;
 	default:
 		BOOST_THROW_EXCEPTION(InternalCompilerError() << errinfo_comment("Unknown kind of magic."));
diff --git a/libsolidity/Types.h b/libsolidity/Types.h
index 853bd6889..e7601fde8 100644
--- a/libsolidity/Types.h
+++ b/libsolidity/Types.h
@@ -43,6 +43,26 @@ using TypePointer = std::shared_ptr<Type const>;
 using FunctionTypePointer = std::shared_ptr<FunctionType const>;
 using TypePointers = std::vector<TypePointer>;
 
+
+/**
+ * Helper class to compute storage offsets of members of structs and contracts.
+ */
+class StorageOffsets
+{
+public:
+	/// Resets the StorageOffsets objects and determines the position in storage for each
+	/// of the elements of @a _types.
+	void computeOffsets(TypePointers const& _types);
+	/// @returns the offset of the given member, might be null if the member is not part of storage.
+	std::pair<u256, unsigned> const* getOffset(size_t _index) const;
+	/// @returns the total number of slots occupied by all members.
+	u256 const& getStorageSize() const { return m_storageSize; }
+
+private:
+	u256 m_storageSize;
+	std::map<size_t, std::pair<u256, unsigned>> m_offsets;
+};
+
 /**
  * List of members of a type.
  */
@@ -53,6 +73,7 @@ public:
 
 	MemberList() {}
 	explicit MemberList(MemberMap const& _members): m_memberTypes(_members) {}
+	MemberList& operator=(MemberList&& _other);
 	TypePointer getMemberType(std::string const& _name) const
 	{
 		for (auto const& it: m_memberTypes)
@@ -60,12 +81,18 @@ public:
 				return it.second;
 		return TypePointer();
 	}
+	/// @returns the offset of the given member in storage slots and bytes inside a slot or
+	/// a nullptr if the member is not part of storage.
+	std::pair<u256, unsigned> const* getMemberStorageOffset(std::string const& _name) const;
+	/// @returns the number of storage slots occupied by the members.
+	u256 const& getStorageSize() const;
 
 	MemberMap::const_iterator begin() const { return m_memberTypes.begin(); }
 	MemberMap::const_iterator end() const { return m_memberTypes.end(); }
 
 private:
 	MemberMap m_memberTypes;
+	mutable std::unique_ptr<StorageOffsets> m_storageOffsets;
 };
 
 /**
@@ -97,6 +124,8 @@ public:
 	/// @returns a pointer to _a or _b if the other is implicitly convertible to it or nullptr otherwise
 	static TypePointer commonType(TypePointer const& _a, TypePointer const& _b);
 
+	/// Calculates the
+
 	virtual Category getCategory() const = 0;
 	virtual bool isImplicitlyConvertibleTo(Type const& _other) const { return *this == _other; }
 	virtual bool isExplicitlyConvertibleTo(Type const& _convertTo) const
@@ -126,9 +155,15 @@ public:
 	unsigned getCalldataEncodedSize() const { return getCalldataEncodedSize(true); }
 	/// @returns true if the type is dynamically encoded in calldata
 	virtual bool isDynamicallySized() const { return false; }
-	/// @returns number of bytes required to hold this value in storage.
+	/// @returns the number of storage slots required to hold this value in storage.
 	/// For dynamically "allocated" types, it returns the size of the statically allocated head,
 	virtual u256 getStorageSize() const { return 1; }
+	/// Multiple small types can be packed into a single storage slot. If such a packing is possible
+	/// this function @returns the size in bytes smaller than 32. Data is moved to the next slot if
+	/// it does not fit.
+	/// In order to avoid computation at runtime of whether such moving is necessary, structs and
+	/// array data (not each element) always start a new slot.
+	virtual unsigned getStorageBytes() const { return 32; }
 	/// Returns true if the type can be stored in storage.
 	virtual bool canBeStored() const { return true; }
 	/// Returns false if the type cannot live outside the storage, i.e. if it includes some mapping.
@@ -179,6 +214,7 @@ public:
 	virtual bool operator==(Type const& _other) const override;
 
 	virtual unsigned getCalldataEncodedSize(bool _padded = true) const override { return _padded ? 32 : m_bits / 8; }
+	virtual unsigned getStorageBytes() const override { return m_bits / 8; }
 	virtual bool isValueType() const override { return true; }
 
 	virtual MemberList const& getMembers() const { return isAddress() ? AddressMemberList : EmptyMemberList; }
@@ -251,6 +287,7 @@ public:
 	virtual TypePointer binaryOperatorResult(Token::Value _operator, TypePointer const& _other) const override;
 
 	virtual unsigned getCalldataEncodedSize(bool _padded) const override { return _padded && m_bytes > 0 ? 32 : m_bytes; }
+	virtual unsigned getStorageBytes() const override { return m_bytes; }
 	virtual bool isValueType() const override { return true; }
 
 	virtual std::string toString() const override { return "bytes" + dev::toString(m_bytes); }
@@ -275,6 +312,7 @@ public:
 	virtual TypePointer binaryOperatorResult(Token::Value _operator, TypePointer const& _other) const override;
 
 	virtual unsigned getCalldataEncodedSize(bool _padded) const { return _padded ? 32 : 1; }
+	virtual unsigned getStorageBytes() const override { return 1; }
 	virtual bool isValueType() const override { return true; }
 
 	virtual std::string toString() const override { return "bool"; }
@@ -284,6 +322,9 @@ public:
 /**
  * The type of an array. The flavours are byte array (bytes), statically- (<type>[<length>])
  * and dynamically-sized array (<type>[]).
+ * In storage, all arrays are packed tightly (as long as more than one elementary type fits in
+ * one slot). Dynamically sized arrays (including byte arrays) start with their size as a uint and
+ * thus start on their own slot.
  */
 class ArrayType: public Type
 {
@@ -345,6 +386,7 @@ public:
 	virtual bool isExplicitlyConvertibleTo(Type const& _convertTo) const override;
 	virtual TypePointer unaryOperatorResult(Token::Value _operator) const override;
 	virtual bool operator==(Type const& _other) const override;
+	virtual unsigned getStorageBytes() const override { return 20; }
 	virtual bool isValueType() const override { return true; }
 	virtual std::string toString() const override;
 
@@ -384,12 +426,12 @@ public:
 	virtual bool operator==(Type const& _other) const override;
 	virtual u256 getStorageSize() const override;
 	virtual bool canLiveOutsideStorage() const override;
-	virtual unsigned getSizeOnStack() const override { return 1; /*@todo*/ }
+	virtual unsigned getSizeOnStack() const override { return 2; }
 	virtual std::string toString() const override;
 
 	virtual MemberList const& getMembers() const override;
 
-	u256 getStorageOffsetOfMember(std::string const& _name) const;
+	std::pair<u256, unsigned> const& getStorageOffsetsOfMember(std::string const& _name) const;
 
 private:
 	StructDefinition const& m_struct;
@@ -408,6 +450,7 @@ public:
 	virtual TypePointer unaryOperatorResult(Token::Value _operator) const override;
 	virtual bool operator==(Type const& _other) const override;
 	virtual unsigned getSizeOnStack() const override { return 1; }
+	virtual unsigned getStorageBytes() const override;
 	virtual std::string toString() const override;
 	virtual bool isValueType() const override { return true; }
 
@@ -477,7 +520,7 @@ public:
 	virtual bool operator==(Type const& _other) const override;
 	virtual std::string toString() const override;
 	virtual bool canBeStored() const override { return false; }
-	virtual u256 getStorageSize() const override { BOOST_THROW_EXCEPTION(InternalCompilerError() << errinfo_comment("Storage size of non-storable function type requested.")); }
+	virtual u256 getStorageSize() const override;
 	virtual bool canLiveOutsideStorage() const override { return false; }
 	virtual unsigned getSizeOnStack() const override;
 	virtual MemberList const& getMembers() const override;
@@ -527,6 +570,7 @@ private:
 
 /**
  * The type of a mapping, there is one distinct type per key/value type pair.
+ * Mappings always occupy their own storage slot, but do not actually use it.
  */
 class MappingType: public Type
 {
@@ -537,6 +581,7 @@ public:
 
 	virtual bool operator==(Type const& _other) const override;
 	virtual std::string toString() const override;
+	virtual unsigned getSizeOnStack() const override { return 2; }
 	virtual bool canLiveOutsideStorage() const override { return false; }
 
 	TypePointer const& getKeyType() const { return m_keyType; }
@@ -560,7 +605,7 @@ public:
 	virtual TypePointer binaryOperatorResult(Token::Value, TypePointer const&) const override { return TypePointer(); }
 	virtual std::string toString() const override { return "void"; }
 	virtual bool canBeStored() const override { return false; }
-	virtual u256 getStorageSize() const override { BOOST_THROW_EXCEPTION(InternalCompilerError() << errinfo_comment("Storage size of non-storable void type requested.")); }
+	virtual u256 getStorageSize() const override;
 	virtual bool canLiveOutsideStorage() const override { return false; }
 	virtual unsigned getSizeOnStack() const override { return 0; }
 };
@@ -580,7 +625,7 @@ public:
 	virtual TypePointer binaryOperatorResult(Token::Value, TypePointer const&) const override { return TypePointer(); }
 	virtual bool operator==(Type const& _other) const override;
 	virtual bool canBeStored() const override { return false; }
-	virtual u256 getStorageSize() const override { BOOST_THROW_EXCEPTION(InternalCompilerError() << errinfo_comment("Storage size of non-storable type type requested.")); }
+	virtual u256 getStorageSize() const override;
 	virtual bool canLiveOutsideStorage() const override { return false; }
 	virtual unsigned getSizeOnStack() const override { return 0; }
 	virtual std::string toString() const override { return "type(" + m_actualType->toString() + ")"; }
@@ -606,7 +651,7 @@ public:
 
 	virtual TypePointer binaryOperatorResult(Token::Value, TypePointer const&) const override { return TypePointer(); }
 	virtual bool canBeStored() const override { return false; }
-	virtual u256 getStorageSize() const override { BOOST_THROW_EXCEPTION(InternalCompilerError() << errinfo_comment("Storage size of non-storable type type requested.")); }
+	virtual u256 getStorageSize() const override;
 	virtual bool canLiveOutsideStorage() const override { return false; }
 	virtual unsigned getSizeOnStack() const override { return 0; }
 	virtual bool operator==(Type const& _other) const override;
diff --git a/test/SolidityEndToEndTest.cpp b/test/SolidityEndToEndTest.cpp
index 8ccf9b3fe..a07b78872 100644
--- a/test/SolidityEndToEndTest.cpp
+++ b/test/SolidityEndToEndTest.cpp
@@ -534,6 +534,27 @@ BOOST_AUTO_TEST_CASE(empty_string_on_stack)
 	BOOST_CHECK(callContractFunction("run(bytes0,uint8)", string(), byte(0x02)) == encodeArgs(0x2, string(""), string("abc\0")));
 }
 
+BOOST_AUTO_TEST_CASE(inc_dec_operators)
+{
+	char const* sourceCode = R"(
+		contract test {
+			uint8 x;
+			uint v;
+			function f() returns (uint r) {
+				uint a = 6;
+				r = a;
+				r += (a++) * 0x10;
+				r += (++a) * 0x100;
+				v = 3;
+				r += (v++) * 0x1000;
+				r += (++v) * 0x10000;
+			}
+		}
+	)";
+	compileAndRun(sourceCode);
+	BOOST_CHECK(callContractFunction("f()") == encodeArgs(0x53866));
+}
+
 BOOST_AUTO_TEST_CASE(state_smoke_test)
 {
 	char const* sourceCode = "contract test {\n"
@@ -970,18 +991,20 @@ BOOST_AUTO_TEST_CASE(multiple_elementary_accessors)
 
 BOOST_AUTO_TEST_CASE(complex_accessors)
 {
-	char const* sourceCode = "contract test {\n"
-							 "  mapping(uint256 => bytes4) public to_string_map;\n"
-							 "  mapping(uint256 => bool) public to_bool_map;\n"
-							 "  mapping(uint256 => uint256) public to_uint_map;\n"
-							 "  mapping(uint256 => mapping(uint256 => uint256)) public to_multiple_map;\n"
-							 "  function test() {\n"
-							 "    to_string_map[42] = \"24\";\n"
-							 "    to_bool_map[42] = false;\n"
-							 "    to_uint_map[42] = 12;\n"
-							 "    to_multiple_map[42][23] = 31;\n"
-							 "  }\n"
-							 "}\n";
+	char const* sourceCode = R"(
+		contract test {
+			mapping(uint256 => bytes4) public to_string_map;
+			mapping(uint256 => bool) public to_bool_map;
+			mapping(uint256 => uint256) public to_uint_map;
+			mapping(uint256 => mapping(uint256 => uint256)) public to_multiple_map;
+			function test() {
+				to_string_map[42] = "24";
+				to_bool_map[42] = false;
+				to_uint_map[42] = 12;
+				to_multiple_map[42][23] = 31;
+			}
+		}
+	)";
 	compileAndRun(sourceCode);
 	BOOST_CHECK(callContractFunction("to_string_map(uint256)", 42) == encodeArgs("24"));
 	BOOST_CHECK(callContractFunction("to_bool_map(uint256)", 42) == encodeArgs(false));
@@ -2502,7 +2525,7 @@ BOOST_AUTO_TEST_CASE(struct_copy)
 		contract c {
 			struct Nested { uint x; uint y; }
 			struct Struct { uint a; mapping(uint => Struct) b; Nested nested; uint c; }
-			mapping(uint => Struct) public data;
+			mapping(uint => Struct) data;
 			function set(uint k) returns (bool) {
 				data[k].a = 1;
 				data[k].nested.x = 3;
@@ -3248,6 +3271,130 @@ BOOST_AUTO_TEST_CASE(constant_variables)
 	})";
 	compileAndRun(sourceCode);
 }
+
+BOOST_AUTO_TEST_CASE(packed_storage_structs_uint)
+{
+	char const* sourceCode = R"(
+		contract C {
+			struct str { uint8 a; uint16 b; uint248 c; }
+			str data;
+			function test() returns (uint) {
+				data.a = 2;
+				if (data.a != 2) return 2;
+				data.b = 0xabcd;
+				if (data.b != 0xabcd) return 3;
+				data.c = 0x1234567890;
+				if (data.c != 0x1234567890) return 4;
+				if (data.a != 2) return 5;
+				data.a = 8;
+				if (data.a != 8) return 6;
+				if (data.b != 0xabcd) return 7;
+				data.b = 0xdcab;
+				if (data.b != 0xdcab) return 8;
+				if (data.c != 0x1234567890) return 9;
+				data.c = 0x9876543210;
+				if (data.c != 0x9876543210) return 10;
+				return 1;
+			}
+		}
+	)";
+	compileAndRun(sourceCode);
+	BOOST_CHECK(callContractFunction("test()") == encodeArgs(1));
+}
+
+BOOST_AUTO_TEST_CASE(packed_storage_structs_enum)
+{
+	char const* sourceCode = R"(
+		contract C {
+			enum small { A, B, C, D }
+			enum larger { A, B, C, D, E}
+			struct str { small a; small b; larger c; larger d; }
+			str data;
+			function test() returns (uint) {
+				data.a = small.B;
+				if (data.a != small.B) return 2;
+				data.b = small.C;
+				if (data.b != small.C) return 3;
+				data.c = larger.D;
+				if (data.c != larger.D) return 4;
+				if (data.a != small.B) return 5;
+				data.a = small.C;
+				if (data.a != small.C) return 6;
+				if (data.b != small.C) return 7;
+				data.b = small.D;
+				if (data.b != small.D) return 8;
+				if (data.c != larger.D) return 9;
+				data.c = larger.B;
+				if (data.c != larger.B) return 10;
+				return 1;
+			}
+		}
+	)";
+	compileAndRun(sourceCode);
+	BOOST_CHECK(callContractFunction("test()") == encodeArgs(1));
+}
+
+BOOST_AUTO_TEST_CASE(packed_storage_structs_bytes)
+{
+	char const* sourceCode = R"(
+		contract C {
+			struct s1 { byte a; byte b; bytes10 c; bytes9 d; bytes10 e; }
+			struct s2 { byte a; s1 inner; byte b; byte c; }
+			byte x;
+			s2 data;
+			byte y;
+			function test() returns (bool) {
+				x = 1;
+				data.a = 2;
+				data.inner.a = 3;
+				data.inner.b = 4;
+				data.inner.c = "1234567890";
+				data.inner.d = "123456789";
+				data.inner.e = "abcdefghij";
+				data.b = 5;
+				data.c = 6;
+				y = 7;
+				return x == 1 && data.a == 2 && data.inner.a == 3 && data.inner.b == 4 &&
+					data.inner.c == "1234567890" && data.inner.d == "123456789" &&
+					data.inner.e == "abcdefghij" && data.b == 5 && data.c == 6 && y == 7;
+			}
+		}
+	)";
+	compileAndRun(sourceCode);
+	BOOST_CHECK(callContractFunction("test()") == encodeArgs(true));
+}
+
+BOOST_AUTO_TEST_CASE(packed_storage_structs_delete)
+{
+	char const* sourceCode = R"(
+		contract C {
+			struct str { uint8 a; uint16 b; uint8 c; }
+			uint8 x;
+			uint16 y;
+			str data;
+			function test() returns (uint) {
+				x = 1;
+				y = 2;
+				data.a = 2;
+				data.b = 0xabcd;
+				data.c = 0xfa;
+				if (x != 1 || y != 2 || data.a != 2 || data.b != 0xabcd || data.c != 0xfa)
+					return 2;
+				delete y;
+				delete data.b;
+				if (x != 1 || y != 0 || data.a != 2 || data.b != 0 || data.c != 0xfa)
+					return 3;
+				delete x;
+				delete data;
+				return 1;
+			}
+		}
+	)";
+	compileAndRun(sourceCode);
+	BOOST_CHECK(callContractFunction("test()") == encodeArgs(1));
+	BOOST_CHECK(m_state.storage(m_contractAddress).empty());
+}
+
 BOOST_AUTO_TEST_SUITE_END()
 
 }
diff --git a/test/SolidityOptimizer.cpp b/test/SolidityOptimizer.cpp
index 41ec1f90c..85b77d210 100644
--- a/test/SolidityOptimizer.cpp
+++ b/test/SolidityOptimizer.cpp
@@ -120,7 +120,7 @@ BOOST_AUTO_TEST_CASE(unused_expressions)
 				data;
 			}
 		})";
-	compileBothVersions(33, sourceCode);
+	compileBothVersions(36, sourceCode);
 	compareVersions("f()");
 }
 
diff --git a/test/SolidityTypes.cpp b/test/SolidityTypes.cpp
new file mode 100644
index 000000000..8defd1d89
--- /dev/null
+++ b/test/SolidityTypes.cpp
@@ -0,0 +1,82 @@
+/*
+	This file is part of cpp-ethereum.
+
+	cpp-ethereum is free software: you can redistribute it and/or modify
+	it under the terms of the GNU General Public License as published by
+	the Free Software Foundation, either version 3 of the License, or
+	(at your option) any later version.
+
+	cpp-ethereum is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+	GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with cpp-ethereum.  If not, see <http://www.gnu.org/licenses/>.
+*/
+/**
+ * @author Christian <c@ethdev.com>
+ * @date 2015
+ * Unit tests for the type system of Solidity.
+ */
+
+#include <libsolidity/Types.h>
+#include <boost/test/unit_test.hpp>
+
+using namespace std;
+
+namespace dev
+{
+namespace solidity
+{
+namespace test
+{
+
+BOOST_AUTO_TEST_SUITE(SolidityTypes)
+
+BOOST_AUTO_TEST_CASE(storage_layout_simple)
+{
+	MemberList members(MemberList::MemberMap({
+		{string("first"), Type::fromElementaryTypeName("uint128")},
+		{string("second"), Type::fromElementaryTypeName("uint120")},
+		{string("wraps"), Type::fromElementaryTypeName("uint16")}
+	}));
+	BOOST_REQUIRE_EQUAL(u256(2), members.getStorageSize());
+	BOOST_REQUIRE(members.getMemberStorageOffset("first") != nullptr);
+	BOOST_REQUIRE(members.getMemberStorageOffset("second") != nullptr);
+	BOOST_REQUIRE(members.getMemberStorageOffset("wraps") != nullptr);
+	BOOST_CHECK(*members.getMemberStorageOffset("first") == make_pair(u256(0), unsigned(0)));
+	BOOST_CHECK(*members.getMemberStorageOffset("second") == make_pair(u256(0), unsigned(16)));
+	BOOST_CHECK(*members.getMemberStorageOffset("wraps") == make_pair(u256(1), unsigned(0)));
+}
+
+BOOST_AUTO_TEST_CASE(storage_layout_mapping)
+{
+	MemberList members(MemberList::MemberMap({
+		{string("first"), Type::fromElementaryTypeName("uint128")},
+		{string("second"), make_shared<MappingType>(
+			Type::fromElementaryTypeName("uint8"),
+			Type::fromElementaryTypeName("uint8")
+		)},
+		{string("third"), Type::fromElementaryTypeName("uint16")},
+		{string("final"), make_shared<MappingType>(
+			Type::fromElementaryTypeName("uint8"),
+			Type::fromElementaryTypeName("uint8")
+		)},
+	}));
+	BOOST_REQUIRE_EQUAL(u256(4), members.getStorageSize());
+	BOOST_REQUIRE(members.getMemberStorageOffset("first") != nullptr);
+	BOOST_REQUIRE(members.getMemberStorageOffset("second") != nullptr);
+	BOOST_REQUIRE(members.getMemberStorageOffset("third") != nullptr);
+	BOOST_REQUIRE(members.getMemberStorageOffset("final") != nullptr);
+	BOOST_CHECK(*members.getMemberStorageOffset("first") == make_pair(u256(0), unsigned(0)));
+	BOOST_CHECK(*members.getMemberStorageOffset("second") == make_pair(u256(1), unsigned(0)));
+	BOOST_CHECK(*members.getMemberStorageOffset("third") == make_pair(u256(2), unsigned(0)));
+	BOOST_CHECK(*members.getMemberStorageOffset("final") == make_pair(u256(3), unsigned(0)));
+}
+
+BOOST_AUTO_TEST_SUITE_END()
+
+}
+}
+}