diff --git a/libdevcore/CommonData.h b/libdevcore/CommonData.h
index 3dd5edab7..87d2f5e28 100644
--- a/libdevcore/CommonData.h
+++ b/libdevcore/CommonData.h
@@ -113,7 +113,7 @@ inline bytes toBigEndian(u160 _val) { bytes ret(20); toBigEndian(_val, ret); ret
 /// Convenience function for toBigEndian.
 /// @returns a byte array just big enough to represent @a _val.
 template <class _T>
-inline bytes toCompactBigEndian(_T _val, unsigned _min = 1)
+inline bytes toCompactBigEndian(_T _val, unsigned _min = 0)
 {
 	int i = 0;
 	for (_T v = _val; v; ++i, v >>= 8) {}
diff --git a/libdevcore/CommonJS.cpp b/libdevcore/CommonJS.cpp
index 157dfd91e..ee2074cd1 100644
--- a/libdevcore/CommonJS.cpp
+++ b/libdevcore/CommonJS.cpp
@@ -42,25 +42,22 @@ bytes padded(bytes _b, unsigned _l)
 {
 	while (_b.size() < _l)
 		_b.insert(_b.begin(), 0);
-	while (_b.size() < _l)
-		_b.push_back(0);
 	return asBytes(asString(_b).substr(_b.size() - std::max(_l, _l)));
 }
 
 bytes unpadded(bytes _b)
 {
-	auto p = asString(_b).find_first_not_of("0");
+	auto p = asString(_b).find_last_not_of((char)0);
 	_b.resize(p == std::string::npos ? 0 : (p + 1));
 	return _b;
 }
 
-std::string unpadded(std::string _b)
+std::string unpadLeft(std::string _b)
 {
 	auto p = _b.find_first_not_of('0');
 	if (p == std::string::npos)
 		return "0";
-	_b = _b.substr(p, _b.length() - 1);
-	return _b;
+	return _b.substr(p, _b.length() - 1);
 }
 
 std::string prettyU256(u256 _n)
diff --git a/libdevcore/CommonJS.h b/libdevcore/CommonJS.h
index ed3a77181..9491bd4b7 100644
--- a/libdevcore/CommonJS.h
+++ b/libdevcore/CommonJS.h
@@ -46,12 +46,19 @@ inline std::string toJS(dev::bytes const& _n)
 	return "0x" + dev::toHex(_n);
 }
 
+/// Convert string to byte array.
 bytes jsToBytes(std::string const& _s);
+/// Add '0' on the head of _b until _l.
 bytes padded(bytes _b, unsigned _l);
+/// Removing all trailing '0'.
 bytes unpadded(bytes _s);
-std::string unpadded(std::string _s);
+/// Remove all '0' on the head of _s.
+std::string unpadLeft(std::string _s);
+/// Convert u256 to readable string.
 std::string prettyU256(u256 _n);
+/// Convert h256 to readable string.
 std::string fromRaw(h256 _n, unsigned* _inc = nullptr);
+/// Convert string to Address (h160).
 Address fromString(std::string const& _a);
 
 template <unsigned N> FixedHash<N> jsToFixed(std::string const& _s)
diff --git a/mix/ContractCallDataEncoder.cpp b/mix/ContractCallDataEncoder.cpp
index c631793d4..b83a0c582 100644
--- a/mix/ContractCallDataEncoder.cpp
+++ b/mix/ContractCallDataEncoder.cpp
@@ -75,7 +75,7 @@ QList<QVariableDefinition*> ContractCallDataEncoder::decode(QList<QVariableDecla
 		QVariableDeclaration* dec = (QVariableDeclaration*)_returnParameters.at(k);
 		int padding = this->padding(dec->type());
 		std::string rawParam = returnValue.substr(0, padding * 2);
-		r.append(new QVariableDefinition(dec, convertToReadable(unpadded(rawParam), dec)));
+		r.append(new QVariableDefinition(dec, convertToReadable(unpadLeft(rawParam), dec)));
 		returnValue = returnValue.substr(rawParam.length(), returnValue.length() - 1);
 	}
 	return r;