diff --git a/libevmjit/Arith256.cpp b/libevmjit/Arith256.cpp
index 941a54fbf..862c8452e 100644
--- a/libevmjit/Arith256.cpp
+++ b/libevmjit/Arith256.cpp
@@ -29,10 +29,8 @@ Arith256::Arith256(llvm::IRBuilder<>& _builder) :
 	using Linkage = GlobalValue::LinkageTypes;
 
 	llvm::Type* arg2Types[] = {Type::WordPtr, Type::WordPtr, Type::WordPtr};
-	llvm::Type* arg3Types[] = {Type::WordPtr, Type::WordPtr, Type::WordPtr, Type::WordPtr};
 
 	m_mul = Function::Create(FunctionType::get(Type::Void, arg2Types, false), Linkage::ExternalLinkage, "arith_mul", getModule());
-	m_addmod = Function::Create(FunctionType::get(Type::Void, arg3Types, false), Linkage::ExternalLinkage, "arith_addmod", getModule());
 }
 
 void Arith256::debug(llvm::Value* _value, char _c)
@@ -210,6 +208,36 @@ llvm::Function* Arith256::getExpFunc()
 	return m_exp;
 }
 
+llvm::Function* Arith256::getAddModFunc()
+{
+	if (!m_addmod)
+	{
+		auto i512Ty = m_builder.getIntNTy(512);
+		llvm::Type* argTypes[] = {Type::Word, Type::Word, Type::Word};
+		m_addmod = llvm::Function::Create(llvm::FunctionType::get(Type::Word, argTypes, false), llvm::Function::PrivateLinkage, "addmod", getModule());
+
+		auto x = &m_addmod->getArgumentList().front();
+		x->setName("x");
+		auto y = x->getNextNode();
+		y->setName("y");
+		auto mod = y->getNextNode();
+		mod->setName("m");
+
+		InsertPointGuard guard{m_builder};
+
+		auto entryBB = llvm::BasicBlock::Create(m_builder.getContext(), {}, m_addmod);
+		m_builder.SetInsertPoint(entryBB);
+		auto x512 = m_builder.CreateZExt(x, i512Ty, "x512");
+		auto y512 = m_builder.CreateZExt(y, i512Ty, "y512");
+		auto m512 = m_builder.CreateZExt(mod, i512Ty, "m512");
+		auto s = m_builder.CreateAdd(x512, y512, "s");
+		auto d = createCall(getDivFunc(i512Ty), {s, m512});
+		auto r = m_builder.CreateExtractValue(d, 1, "r");
+		m_builder.CreateRet(r);
+	}
+	return m_addmod;
+}
+
 llvm::Function* Arith256::getMulModFunc()
 {
 	if (!m_mulmod)
@@ -247,7 +275,6 @@ llvm::Function* Arith256::getMulModFunc()
 	return m_mulmod;
 }
 
-
 llvm::Value* Arith256::binaryOp(llvm::Function* _op, llvm::Value* _arg1, llvm::Value* _arg2)
 {
 	m_builder.CreateStore(_arg1, m_arg1);
@@ -256,15 +283,6 @@ llvm::Value* Arith256::binaryOp(llvm::Function* _op, llvm::Value* _arg1, llvm::V
 	return m_builder.CreateLoad(m_result);
 }
 
-llvm::Value* Arith256::ternaryOp(llvm::Function* _op, llvm::Value* _arg1, llvm::Value* _arg2, llvm::Value* _arg3)
-{
-	m_builder.CreateStore(_arg1, m_arg1);
-	m_builder.CreateStore(_arg2, m_arg2);
-	m_builder.CreateStore(_arg3, m_arg3);
-	m_builder.CreateCall4(_op, m_arg1, m_arg2, m_arg3, m_result);
-	return m_builder.CreateLoad(m_result);
-}
-
 llvm::Value* Arith256::mul(llvm::Value* _arg1, llvm::Value* _arg2)
 {
 	return binaryOp(m_mul, _arg1, _arg2);
@@ -307,7 +325,7 @@ llvm::Value* Arith256::exp(llvm::Value* _arg1, llvm::Value* _arg2)
 
 llvm::Value* Arith256::addmod(llvm::Value* _arg1, llvm::Value* _arg2, llvm::Value* _arg3)
 {
-	return ternaryOp(m_addmod, _arg1, _arg2, _arg3);
+	return createCall(getAddModFunc(), {_arg1, _arg2, _arg3});
 }
 
 llvm::Value* Arith256::mulmod(llvm::Value* _arg1, llvm::Value* _arg2, llvm::Value* _arg3)
@@ -402,46 +420,14 @@ namespace
 
 		return {lo, (uint128)mid, hi};
 	}
-
-	inline void mul(i256* x, i256* y)
-	{
-		auto a = (uint256*) x;
-		auto b = (uint256*) y;
-		*a = mul(*a, *b);
-	}
-
-	bool isZero(i256 const* _n)
-	{
-		return _n->a == 0 && _n->b == 0 && _n->c == 0 && _n->d == 0;
-	}
-
-	const auto nLimbs = sizeof(i256) / sizeof(mp_limb_t);
-
-	int countLimbs(i256 const* _n)
-	{
-		static const auto limbsInWord = sizeof(_n->a) / sizeof(mp_limb_t);
-		static_assert(limbsInWord == 1, "E?");
-
-		int l = nLimbs;
-		if (_n->d != 0) return l;
-		l -= limbsInWord;
-		if (_n->c != 0) return l;
-		l -= limbsInWord;
-		if (_n->b != 0) return l;
-		l -= limbsInWord;
-		if (_n->a != 0) return l;
-		return 0;
-	}
 }
 
 }
 }
 }
 
-
 extern "C"
 {
-
 	using namespace dev::eth::jit;
 
 	EXPORT void debug(uint64_t a, uint64_t b, uint64_t c, uint64_t d, char z)
@@ -458,24 +444,4 @@ extern "C"
 	{
 		*o_result = mul512(*_arg1, *_arg2);
 	}
-
-	EXPORT void arith_addmod(i256* _arg1, i256* _arg2, i256* _arg3, i256* o_result)
-	{
-		*o_result = {};
-		if (isZero(_arg3))
-			return;
-
-		mpz_t x{nLimbs, countLimbs(_arg1), reinterpret_cast<mp_limb_t*>(_arg1)};
-		mpz_t y{nLimbs, countLimbs(_arg2), reinterpret_cast<mp_limb_t*>(_arg2)};
-		mpz_t m{nLimbs, countLimbs(_arg3), reinterpret_cast<mp_limb_t*>(_arg3)};
-		mpz_t z{nLimbs, 0, reinterpret_cast<mp_limb_t*>(o_result)};
-		static mp_limb_t s_limbs[nLimbs + 1] = {};
-		static mpz_t s{nLimbs + 1, 0, &s_limbs[0]};
-
-		mpz_add(s, x, y);
-		mpz_tdiv_r(z, s, m);
-	}
-
 }
-
-
diff --git a/libevmjit/Arith256.h b/libevmjit/Arith256.h
index ae87d11f2..5852137f8 100644
--- a/libevmjit/Arith256.h
+++ b/libevmjit/Arith256.h
@@ -26,17 +26,17 @@ public:
 private:
 	llvm::Function* getDivFunc(llvm::Type* _type);
 	llvm::Function* getExpFunc();
+	llvm::Function* getAddModFunc();
 	llvm::Function* getMulModFunc();
 
 	llvm::Value* binaryOp(llvm::Function* _op, llvm::Value* _arg1, llvm::Value* _arg2);
-	llvm::Value* ternaryOp(llvm::Function* _op, llvm::Value* _arg1, llvm::Value* _arg2, llvm::Value* _arg3);
 
 	llvm::Function* m_mul;
-	llvm::Function* m_addmod;
 
 	llvm::Function* m_div = nullptr;
 	llvm::Function* m_div512 = nullptr;
 	llvm::Function* m_exp = nullptr;
+	llvm::Function* m_addmod = nullptr;
 	llvm::Function* m_mulmod = nullptr;
 	llvm::Function* m_debug = nullptr;