diff --git a/evmjit/CMakeLists.txt b/evmjit/CMakeLists.txt
index acb113207e..4888de5238 100644
--- a/evmjit/CMakeLists.txt
+++ b/evmjit/CMakeLists.txt
@@ -4,17 +4,18 @@ project(evmjit)
 
 set_property(GLOBAL PROPERTY USE_FOLDERS ON)
 
-if ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "MSVC")
-else ()
-	set(CMAKE_CXX_FLAGS "-std=c++11 -Wall -Wno-unknown-pragmas -Wextra -DSHAREDLIB -fPIC")
+if(CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
+else()
+	set(CMAKE_CXX_FLAGS "-std=c++11 -Wall -Wno-unknown-pragmas -Wextra -fPIC")
 endif()
 
-if(APPLE)
-	set(CMAKE_SHARED_LINKER_FLAGS "-undefined dynamic_lookup")
+if(CMAKE_SYSTEM_NAME STREQUAL "Linux")
+	# Do not allow unresovled symbols in shared library (default on linux)
+	set(CMAKE_SHARED_LINKER_FLAGS "-Wl,--no-undefined")
 endif()
 
 # LLVM
-if(LLVM_DIR)	# local LLVM build
+if(LLVM_DIR OR APPLE)	# local LLVM build
 	find_package(LLVM REQUIRED CONFIG)
 	message(STATUS "Found LLVM ${LLVM_PACKAGE_VERSION}")
 	message(STATUS "Using LLVMConfig.cmake in: ${LLVM_DIR}")
@@ -28,11 +29,9 @@ else()
 	message(STATUS "LLVM include dirs: ${LLVM_INCLUDE_DIRS}")
 	set(LLVM_LIBS "-lLLVMBitWriter -lLLVMX86CodeGen -lLLVMSelectionDAG -lLLVMAsmPrinter -lLLVMCodeGen -lLLVMScalarOpts -lLLVMInstCombine -lLLVMTransformUtils -lLLVMipa -lLLVMAnalysis -lLLVMX86AsmParser -lLLVMX86Desc -lLLVMX86Info -lLLVMX86AsmPrinter -lLLVMX86Utils -lLLVMMCJIT -lLLVMTarget -lLLVMRuntimeDyld -lLLVMObject -lLLVMMCParser -lLLVMBitReader -lLLVMExecutionEngine -lLLVMMC -lLLVMCore -lLLVMSupport -lz -lpthread -lffi -ltinfo -ldl -lm")
 	add_definitions(-D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS)
+	link_directories(/usr/lib/llvm-3.5/lib)
 endif()
 
-# Boost
-find_package(Boost REQUIRED)
-
 add_subdirectory(libevmjit)
 
 if(EVMJIT_CPP)
diff --git a/evmjit/libevmjit-cpp/CMakeLists.txt b/evmjit/libevmjit-cpp/CMakeLists.txt
index 25be95177e..58375e4ee4 100644
--- a/evmjit/libevmjit-cpp/CMakeLists.txt
+++ b/evmjit/libevmjit-cpp/CMakeLists.txt
@@ -1,5 +1,8 @@
 set(TARGET_NAME evmjit-cpp)
 
+# Boost
+find_package(Boost REQUIRED)
+
 set(SOURCES
     Env.cpp     
     JitVM.cpp   JitVM.h
diff --git a/evmjit/libevmjit-cpp/Env.cpp b/evmjit/libevmjit-cpp/Env.cpp
index 6320aa2228..f898977929 100644
--- a/evmjit/libevmjit-cpp/Env.cpp
+++ b/evmjit/libevmjit-cpp/Env.cpp
@@ -3,7 +3,7 @@
 #include <libevm/FeeStructure.h>
 #include <libevm/ExtVMFace.h>
 
-#include <evmjit/libevmjit/Utils.h>
+#include "Utils.h"
 
 extern "C"
 {
@@ -16,7 +16,6 @@ extern "C"
 	using namespace dev;
 	using namespace dev::eth;
 	using jit::i256;
-	using jit::eth2llvm;
 
 	EXPORT void env_sload(ExtVMFace* _env, i256* _index, i256* o_value)
 	{
@@ -89,7 +88,7 @@ extern "C"
 		*o_hash = hash;
 	}
 
-	EXPORT byte const* env_getExtCode(ExtVMFace* _env, h256* _addr256, uint64_t* o_size)
+	EXPORT byte const* env_extcode(ExtVMFace* _env, h256* _addr256, uint64_t* o_size)
 	{
 		auto addr = right160(*_addr256);
 		auto& code = _env->codeAt(addr);
diff --git a/evmjit/libevmjit-cpp/JitVM.cpp b/evmjit/libevmjit-cpp/JitVM.cpp
index dda8133a8d..ededbff527 100644
--- a/evmjit/libevmjit-cpp/JitVM.cpp
+++ b/evmjit/libevmjit-cpp/JitVM.cpp
@@ -2,7 +2,7 @@
 #include "JitVM.h"
 #include <libevm/VM.h>
 #include <evmjit/libevmjit/ExecutionEngine.h>
-#include <evmjit/libevmjit/Utils.h>
+#include "Utils.h"
 
 namespace dev
 {
@@ -13,28 +13,28 @@ bytesConstRef JitVM::go(ExtVMFace& _ext, OnOpFunc const&, uint64_t)
 {
 	using namespace jit;
 
-	m_data.set(RuntimeData::Gas, m_gas);
-	m_data.set(RuntimeData::Address, fromAddress(_ext.myAddress));
-	m_data.set(RuntimeData::Caller, fromAddress(_ext.caller));
-	m_data.set(RuntimeData::Origin, fromAddress(_ext.origin));
-	m_data.set(RuntimeData::CallValue, _ext.value);
-	m_data.set(RuntimeData::CallDataSize, _ext.data.size());
-	m_data.set(RuntimeData::GasPrice, _ext.gasPrice);
-	m_data.set(RuntimeData::CoinBase, fromAddress(_ext.currentBlock.coinbaseAddress));
-	m_data.set(RuntimeData::TimeStamp, _ext.currentBlock.timestamp);
-	m_data.set(RuntimeData::Number, _ext.currentBlock.number);
-	m_data.set(RuntimeData::Difficulty, _ext.currentBlock.difficulty);
-	m_data.set(RuntimeData::GasLimit, _ext.currentBlock.gasLimit);
-	m_data.set(RuntimeData::CodeSize, _ext.code.size());
+	m_data.elems[RuntimeData::Gas]          = eth2llvm(m_gas);
+	m_data.elems[RuntimeData::Address]      = eth2llvm(fromAddress(_ext.myAddress));
+	m_data.elems[RuntimeData::Caller]       = eth2llvm(fromAddress(_ext.caller));
+	m_data.elems[RuntimeData::Origin]       = eth2llvm(fromAddress(_ext.origin));
+	m_data.elems[RuntimeData::CallValue]    = eth2llvm(_ext.value);
+	m_data.elems[RuntimeData::CallDataSize] = eth2llvm(_ext.data.size());
+	m_data.elems[RuntimeData::GasPrice]     = eth2llvm(_ext.gasPrice);
+	m_data.elems[RuntimeData::CoinBase]     = eth2llvm(fromAddress(_ext.currentBlock.coinbaseAddress));
+	m_data.elems[RuntimeData::TimeStamp]    = eth2llvm(_ext.currentBlock.timestamp);
+	m_data.elems[RuntimeData::Number]       = eth2llvm(_ext.currentBlock.number);
+	m_data.elems[RuntimeData::Difficulty]   = eth2llvm(_ext.currentBlock.difficulty);
+	m_data.elems[RuntimeData::GasLimit]     = eth2llvm(_ext.currentBlock.gasLimit);
+	m_data.elems[RuntimeData::CodeSize]     = eth2llvm(_ext.code.size());
 	m_data.callData = _ext.data.data();
-	m_data.code = _ext.code.data();
+	m_data.code     = _ext.code.data();
 
 	auto env = reinterpret_cast<Env*>(&_ext);
 	auto exitCode = m_engine.run(_ext.code, &m_data, env);
 	switch (exitCode)
 	{
 	case ReturnCode::Suicide:
-		_ext.suicide(right160(m_data.get(RuntimeData::SuicideDestAddress)));
+		_ext.suicide(right160(llvm2eth(m_data.elems[RuntimeData::SuicideDestAddress])));
 		break;
 
 	case ReturnCode::BadJumpDestination:
@@ -50,7 +50,7 @@ bytesConstRef JitVM::go(ExtVMFace& _ext, OnOpFunc const&, uint64_t)
 	}
 
 	m_gas = llvm2eth(m_data.elems[RuntimeData::Gas]);
-	return {m_engine.returnData.data(), m_engine.returnData.size()};  // TODO: This all bytesConstRef is problematic, review.
+	return {std::get<0>(m_engine.returnData), std::get<1>(m_engine.returnData)};
 }
 
 }
diff --git a/evmjit/libevmjit-cpp/Utils.h b/evmjit/libevmjit-cpp/Utils.h
new file mode 100644
index 0000000000..ac796920b4
--- /dev/null
+++ b/evmjit/libevmjit-cpp/Utils.h
@@ -0,0 +1,38 @@
+#pragma once
+
+#include <evmjit/libevmjit/Common.h>
+
+namespace dev
+{
+namespace eth
+{
+
+inline u256 llvm2eth(jit::i256 _i)
+{
+	u256 u = 0;
+	u |= _i.d;
+	u <<= 64;
+	u |= _i.c;
+	u <<= 64;
+	u |= _i.b;
+	u <<= 64;
+	u |= _i.a;
+	return u;
+}
+
+inline jit::i256 eth2llvm(u256 _u)
+{
+	jit::i256 i;
+	u256 mask = 0xFFFFFFFFFFFFFFFF;
+	i.a = static_cast<uint64_t>(_u & mask);
+	_u >>= 64;
+	i.b = static_cast<uint64_t>(_u & mask);
+	_u >>= 64;
+	i.c = static_cast<uint64_t>(_u & mask);
+	_u >>= 64;
+	i.d = static_cast<uint64_t>(_u & mask);
+	return i;
+}
+
+}
+}
diff --git a/evmjit/libevmjit/Arith256.cpp b/evmjit/libevmjit/Arith256.cpp
index b5319bda71..adb6cf9d54 100644
--- a/evmjit/libevmjit/Arith256.cpp
+++ b/evmjit/libevmjit/Arith256.cpp
@@ -1,8 +1,10 @@
 #include "Arith256.h"
 #include "Runtime.h"
 #include "Type.h"
+#include "Endianness.h"
 
 #include <llvm/IR/Function.h>
+#include <gmp.h>
 
 namespace dev
 {
@@ -63,6 +65,8 @@ llvm::Value* Arith256::mul(llvm::Value* _arg1, llvm::Value* _arg2)
 
 llvm::Value* Arith256::div(llvm::Value* _arg1, llvm::Value* _arg2)
 {
+
+	//return Endianness::toNative(m_builder, binaryOp(m_div, Endianness::toBE(m_builder, _arg1), Endianness::toBE(m_builder, _arg2)));
 	return binaryOp(m_div, _arg1, _arg2);
 }
 
@@ -98,25 +102,104 @@ llvm::Value* Arith256::mulmod(llvm::Value* _arg1, llvm::Value* _arg2, llvm::Valu
 
 namespace
 {
-	using s256 = boost::multiprecision::int256_t;
+	using uint128 = __uint128_t;
 
-	inline s256 u2s(u256 _u)
+//	uint128 add(uint128 a, uint128 b) { return a + b; }
+//	uint128 mul(uint128 a, uint128 b) { return a * b; }
+//
+//	uint128 mulq(uint64_t x, uint64_t y)
+//	{
+//		return (uint128)x * (uint128)y;
+//	}
+//
+//	uint128 addc(uint64_t x, uint64_t y)
+//	{
+//		return (uint128)x * (uint128)y;
+//	}
+
+	struct uint256
 	{
-		static const bigint c_end = (bigint)1 << 256;
-		static const u256 c_send = (u256)1 << 255;
-		if (_u < c_send)
-			return (s256)_u;
-		else
-			return (s256)-(c_end - _u);
+		uint64_t lo;
+		uint64_t mid;
+		uint128 hi;
+	};
+
+//	uint256 add(uint256 x, uint256 y)
+//	{
+//		auto lo = (uint128) x.lo + y.lo;
+//		auto mid = (uint128) x.mid + y.mid + (lo >> 64);
+//		return {lo, mid, x.hi + y.hi + (mid >> 64)};
+//	}
+
+	uint256 mul(uint256 x, uint256 y)
+	{
+		auto t1 = (uint128) x.lo * y.lo;
+		auto t2 = (uint128) x.lo * y.mid;
+		auto t3 = x.lo * y.hi;
+		auto t4 = (uint128) x.mid * y.lo;
+		auto t5 = (uint128) x.mid * y.mid;
+		auto t6 = x.mid * y.hi;
+		auto t7 = x.hi * y.lo;
+		auto t8 = x.hi * y.mid;
+
+		auto lo = (uint64_t) t1;
+		auto m1 = (t1 >> 64) + (uint64_t) t2;
+		auto m2 = (uint64_t) m1;
+		auto mid = (uint128) m2 + (uint64_t) t4;
+		auto hi = (t2 >> 64) + t3 + (t4 >> 64) + t5 + (t6 << 64) + t7
+			 + (t8 << 64) + (m1 >> 64) + (mid >> 64);
+
+		return {lo, (uint64_t)mid, hi};
 	}
 
-	inline u256 s2u(s256 _u)
+	bool isZero(i256 const* _n)
 	{
-		static const bigint c_end = (bigint)1 << 256;
-		if (_u >= 0)
-			return (u256)_u;
-		else
-			return (u256)(c_end + _u);
+		return _n->a == 0 && _n->b == 0 && _n->c == 0 && _n->d == 0;
+	}
+
+	const auto nLimbs = sizeof(i256) / sizeof(mp_limb_t);
+
+	// FIXME: Not thread-safe
+	static mp_limb_t mod_limbs[] = {0, 0, 0, 0, 1};
+	static_assert(sizeof(mod_limbs) / sizeof(mod_limbs[0]) == nLimbs + 1, "mp_limb_t size mismatch");
+	static const mpz_t mod{nLimbs + 1, nLimbs + 1, &mod_limbs[0]};
+
+	static mp_limb_t tmp_limbs[nLimbs + 2];
+	static mpz_t tmp{nLimbs + 2, 0, &tmp_limbs[0]};
+
+	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;
+	}
+
+	void u2s(mpz_t _u)
+	{
+		if (static_cast<std::make_signed<mp_limb_t>::type>(_u->_mp_d[nLimbs - 1]) < 0)
+		{
+			mpz_sub(tmp, mod, _u);
+			mpz_set(_u, tmp);
+			_u->_mp_size = -_u->_mp_size;
+		}
+	}
+
+	void s2u(mpz_t _s)
+	{
+		if (_s->_mp_size < 0)
+		{
+			mpz_add(tmp, mod, _s);
+			mpz_set(_s, tmp);
+		}
 	}
 }
 
@@ -130,69 +213,120 @@ extern "C"
 
 	using namespace dev::eth::jit;
 
-	EXPORT void arith_mul(i256* _arg1, i256* _arg2, i256* o_result)
+	EXPORT void arith_mul(uint256* _arg1, uint256* _arg2, uint256* o_result)
 	{
-		auto arg1 = llvm2eth(*_arg1);
-		auto arg2 = llvm2eth(*_arg2);
-		*o_result = eth2llvm(arg1 * arg2);
+		*o_result = mul(*_arg1, *_arg2);
 	}
 
 	EXPORT void arith_div(i256* _arg1, i256* _arg2, i256* o_result)
 	{
-		auto arg1 = llvm2eth(*_arg1);
-		auto arg2 = llvm2eth(*_arg2);
-		*o_result = eth2llvm(arg2 == 0 ? arg2 : arg1 / arg2);
+		*o_result = {};
+		if (isZero(_arg2))
+			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 z{nLimbs, 0, reinterpret_cast<mp_limb_t*>(o_result)};
+
+		mpz_tdiv_q(z, x, y);
+
+//		auto arg1 = llvm2eth(*_arg1);
+//		auto arg2 = llvm2eth(*_arg2);
+//		auto res = arg2 == 0 ? arg2 : arg1 / arg2;
+//		std::cout << "DIV " << arg1 << "/" << arg2 << " = " << res << std::endl;
+//		gmp_printf("GMP %Zd / %Zd = %Zd\n", x, y, z);
 	}
 
 	EXPORT void arith_mod(i256* _arg1, i256* _arg2, i256* o_result)
 	{
-		auto arg1 = llvm2eth(*_arg1);
-		auto arg2 = llvm2eth(*_arg2);
-		*o_result = eth2llvm(arg2 == 0 ? arg2 : arg1 % arg2);
+		*o_result = {};
+		if (isZero(_arg2))
+			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 z{nLimbs, 0, reinterpret_cast<mp_limb_t*>(o_result)};
+
+		mpz_tdiv_r(z, x, y);
 	}
 
 	EXPORT void arith_sdiv(i256* _arg1, i256* _arg2, i256* o_result)
 	{
-		auto arg1 = llvm2eth(*_arg1);
-		auto arg2 = llvm2eth(*_arg2);
-		*o_result = eth2llvm(arg2 == 0 ? arg2 : s2u(u2s(arg1) / u2s(arg2)));
+		*o_result = {};
+		if (isZero(_arg2))
+			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 z{nLimbs, 0, reinterpret_cast<mp_limb_t*>(o_result)};
+		u2s(x);
+		u2s(y);
+		mpz_tdiv_q(z, x, y);
+		s2u(z);
 	}
 
 	EXPORT void arith_smod(i256* _arg1, i256* _arg2, i256* o_result)
 	{
-		auto arg1 = llvm2eth(*_arg1);
-		auto arg2 = llvm2eth(*_arg2);
-		*o_result = eth2llvm(arg2 == 0 ? arg2 : s2u(u2s(arg1) % u2s(arg2)));
+		*o_result = {};
+		if (isZero(_arg2))
+			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 z{nLimbs, 0, reinterpret_cast<mp_limb_t*>(o_result)};
+		u2s(x);
+		u2s(y);
+		mpz_tdiv_r(z, x, y);
+		s2u(z);
 	}
 
 	EXPORT void arith_exp(i256* _arg1, i256* _arg2, i256* o_result)
 	{
-		bigint left = llvm2eth(*_arg1);
-		bigint right = llvm2eth(*_arg2);
-		auto ret = static_cast<u256>(boost::multiprecision::powm(left, right, bigint(2) << 256));
-		*o_result = eth2llvm(ret);
+		*o_result = {};
+
+		static mp_limb_t mod_limbs[nLimbs + 1] = {};
+		mod_limbs[nLimbs] = 1;
+		static const mpz_t mod{nLimbs + 1, nLimbs + 1, &mod_limbs[0]};
+
+		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 z{nLimbs, 0, reinterpret_cast<mp_limb_t*>(o_result)};
+
+		mpz_powm(z, x, y, mod);
 	}
 
 	EXPORT void arith_mulmod(i256* _arg1, i256* _arg2, i256* _arg3, i256* o_result)
 	{
-		auto arg1 = llvm2eth(*_arg1);
-		auto arg2 = llvm2eth(*_arg2);
-		auto arg3 = llvm2eth(*_arg3);
-		if (arg3 != 0)
-			*o_result = eth2llvm(u256((bigint(arg1) * bigint(arg2)) % arg3));
-		else
-			*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 p_limbs[nLimbs * 2] = {};
+		static mpz_t p{nLimbs * 2, 0, &p_limbs[0]};
+
+		mpz_mul(p, x, y);
+		mpz_tdiv_r(z, p, m);
 	}
 
 	EXPORT void arith_addmod(i256* _arg1, i256* _arg2, i256* _arg3, i256* o_result)
 	{
-		auto arg1 = llvm2eth(*_arg1);
-		auto arg2 = llvm2eth(*_arg2);
-		auto arg3 = llvm2eth(*_arg3);
-		if (arg3 != 0)
-			*o_result = eth2llvm(u256((bigint(arg1) + bigint(arg2)) % arg3));
-		else
-			*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/evmjit/libevmjit/BasicBlock.cpp b/evmjit/libevmjit/BasicBlock.cpp
index dda0fbc364..5868c0f431 100644
--- a/evmjit/libevmjit/BasicBlock.cpp
+++ b/evmjit/libevmjit/BasicBlock.cpp
@@ -168,16 +168,13 @@ void BasicBlock::synchronizeLocalStack(Stack& _evmStack)
 		if (val == nullptr)
 			continue;
 
-		assert(llvm::isa<llvm::PHINode>(val));
 		llvm::PHINode* phi = llvm::cast<llvm::PHINode>(val);
-		if (! phi->use_empty())
-		{
-			// Insert call to get() just before the PHI node and replace
-			// the uses of PHI with the uses of this new instruction.
-			m_builder.SetInsertPoint(phi);
-			auto newVal = _evmStack.get(idx);
-			phi->replaceAllUsesWith(newVal);
-		}
+		// Insert call to get() just before the PHI node and replace
+		// the uses of PHI with the uses of this new instruction.
+		m_builder.SetInsertPoint(phi);
+		auto newVal = _evmStack.get(idx); // OPT: Value may be never user but we need to check stack heigth
+		                                  //      It is probably a good idea to keep heigth as a local variable accesible by LLVM directly
+		phi->replaceAllUsesWith(newVal);
 		phi->eraseFromParent();
 	}
 
diff --git a/evmjit/libevmjit/BasicBlock.h b/evmjit/libevmjit/BasicBlock.h
index 7a5364a4ea..cda4f89bda 100644
--- a/evmjit/libevmjit/BasicBlock.h
+++ b/evmjit/libevmjit/BasicBlock.h
@@ -57,7 +57,7 @@ public:
 	explicit BasicBlock(std::string _name, llvm::Function* _mainFunc, llvm::IRBuilder<>& _builder, bool isJumpDest);
 
 	BasicBlock(const BasicBlock&) = delete;
-	void operator=(const BasicBlock&) = delete;
+	BasicBlock& operator=(const BasicBlock&) = delete;
 
 	llvm::BasicBlock* llvm() { return m_llvmBB; }
 
@@ -66,6 +66,9 @@ public:
 
 	bool isJumpDest() const { return m_isJumpDest; }
 
+	llvm::Value* getJumpTarget() const { return m_jumpTarget; }
+	void setJumpTarget(llvm::Value* _jumpTarget) { m_jumpTarget = _jumpTarget; }
+
 	LocalStack& localStack() { return m_stack; }
 
 	/// Optimization: propagates values between local stacks in basic blocks
@@ -112,6 +115,9 @@ private:
 	/// Is the basic block a valid jump destination.
 	/// JUMPDEST is the first instruction of the basic block.
 	bool const m_isJumpDest = false;
+
+	/// If block finishes with dynamic jump target index is stored here
+	llvm::Value* m_jumpTarget = nullptr;
 };
 
 }
diff --git a/evmjit/libevmjit/CMakeLists.txt b/evmjit/libevmjit/CMakeLists.txt
index 28b501ee3a..1990ec3987 100644
--- a/evmjit/libevmjit/CMakeLists.txt
+++ b/evmjit/libevmjit/CMakeLists.txt
@@ -2,24 +2,24 @@ set(TARGET_NAME evmjit)
 
 file(GLOB SOURCES "*.cpp")
 file(GLOB HEADERS "*.h")
+set(INTERFACE_HEADERS interface.h)
 source_group("" FILES ${HEADERS})
 source_group("" FILES ${SOURCES})
 
 if (NOT "${CMAKE_CXX_COMPILER_ID}" STREQUAL "MSVC")
 	# Disable rtti for Cache as LLVM has no rtti
 	set_source_files_properties(Cache.cpp PROPERTIES COMPILE_FLAGS -fno-rtti)
-endif ()
+endif()
 
-link_directories(/usr/lib/llvm-3.5/lib)
 add_library(${TARGET_NAME} SHARED ${SOURCES} ${HEADERS})
 set_property(TARGET ${TARGET_NAME} PROPERTY FOLDER "libs")
 
 include_directories(${LLVM_INCLUDE_DIRS})
-include_directories(${Boost_INCLUDE_DIRS})
 
-target_link_libraries(${TARGET_NAME} ${LLVM_LIBS})
+target_link_libraries(${TARGET_NAME} PRIVATE ${LLVM_LIBS})
+target_link_libraries(${TARGET_NAME} PRIVATE gmp)
 
 #set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fno-rtti")
 
-#install( TARGETS ${EXECUTABLE} ARCHIVE DESTINATION lib LIBRARY DESTINATION lib )
-#install( FILES ${HEADERS} DESTINATION include/${EXECUTABLE} )
+install(TARGETS ${TARGET_NAME} LIBRARY DESTINATION lib)
+install(FILES ${INTERFACE_HEADERS} DESTINATION include/${TARGET_NAME})
diff --git a/evmjit/libevmjit/Cache.cpp b/evmjit/libevmjit/Cache.cpp
index 0b725bc24d..0e6fb517a1 100644
--- a/evmjit/libevmjit/Cache.cpp
+++ b/evmjit/libevmjit/Cache.cpp
@@ -36,6 +36,20 @@ std::unique_ptr<llvm::Module> Cache::getObject(std::string const& id)
 	llvm::sys::path::system_temp_directory(false, cachePath);
 	llvm::sys::path::append(cachePath, "evm_objs", id);
 
+#if defined(__GNUC__) && !defined(NDEBUG)
+	llvm::sys::fs::file_status st;
+	auto err = llvm::sys::fs::status(cachePath.str(), st);
+	if (err)
+		return nullptr;
+	auto mtime = st.getLastModificationTime().toEpochTime();
+
+	std::tm tm;
+	strptime(__DATE__ __TIME__, " %b %d %Y %H:%M:%S", &tm);
+	auto btime = (uint64_t)std::mktime(&tm);
+	if (btime > mtime)
+		return nullptr;
+#endif
+
 	if (auto r = llvm::MemoryBuffer::getFile(cachePath.str(), -1, false))
 		lastObject = llvm::MemoryBuffer::getMemBufferCopy(r.get()->getBuffer());
 	else if (r.getError() != std::make_error_code(std::errc::no_such_file_or_directory))
diff --git a/evmjit/libevmjit/Common.h b/evmjit/libevmjit/Common.h
index 1d8451c74d..d0c5822365 100644
--- a/evmjit/libevmjit/Common.h
+++ b/evmjit/libevmjit/Common.h
@@ -1,7 +1,7 @@
 #pragma once
 
 #include <vector>
-#include <boost/multiprecision/cpp_int.hpp>
+#include <tuple>
 
 namespace dev
 {
@@ -12,8 +12,7 @@ namespace jit
 
 using byte = uint8_t;
 using bytes = std::vector<byte>;
-using u256 = boost::multiprecision::uint256_t;
-using bigint = boost::multiprecision::cpp_int;
+using bytes_ref = std::tuple<byte const*, size_t>;
 
 struct NoteChannel {};	// FIXME: Use some log library?
 
@@ -34,7 +33,6 @@ enum class ReturnCode
 };
 
 /// Representation of 256-bit value binary compatible with LLVM i256
-// TODO: Replace with h256
 struct i256
 {
 	uint64_t a = 0;
diff --git a/evmjit/libevmjit/Compiler.cpp b/evmjit/libevmjit/Compiler.cpp
index bfcb9cea10..6286ef92f2 100644
--- a/evmjit/libevmjit/Compiler.cpp
+++ b/evmjit/libevmjit/Compiler.cpp
@@ -4,6 +4,7 @@
 #include <functional>
 #include <fstream>
 #include <chrono>
+#include <sstream>
 
 #include <llvm/ADT/PostOrderIterator.h>
 #include <llvm/IR/CFG.h>
@@ -100,7 +101,7 @@ llvm::BasicBlock* Compiler::getJumpTableBlock()
 		m_jumpTableBlock.reset(new BasicBlock("JumpTable", m_mainFunc, m_builder, true));
 		InsertPointGuard g{m_builder};
 		m_builder.SetInsertPoint(m_jumpTableBlock->llvm());
-		auto dest = m_jumpTableBlock->localStack().pop();
+		auto dest = m_builder.CreatePHI(Type::Word, 8, "target");
 		auto switchInstr = m_builder.CreateSwitch(dest, getBadJumpBlock());
 		for (auto&& p : m_basicBlocks)
 		{
@@ -165,6 +166,26 @@ std::unique_ptr<llvm::Module> Compiler::compile(bytes const& _bytecode, std::str
 
 	removeDeadBlocks();
 
+	// Link jump table target index
+	if (m_jumpTableBlock)
+	{
+		auto phi = llvm::cast<llvm::PHINode>(&m_jumpTableBlock->llvm()->getInstList().front());
+		for (auto predIt = llvm::pred_begin(m_jumpTableBlock->llvm()); predIt != llvm::pred_end(m_jumpTableBlock->llvm()); ++predIt)
+		{
+			BasicBlock* pred = nullptr;
+			for (auto&& p : m_basicBlocks)
+			{
+				if (p.second.llvm() == *predIt)
+				{
+					pred = &p.second;
+					break;
+				}
+			}
+
+			phi->addIncoming(pred->getJumpTarget(), pred->llvm());
+		}
+	}
+
 	dumpCFGifRequired("blocks-init.dot");
 
 	if (m_options.optimizeStack)
@@ -394,7 +415,8 @@ void Compiler::compileBasicBlock(BasicBlock& _basicBlock, bytes const& _bytecode
 
 			value = Endianness::toBE(m_builder, value);
 			auto bytes = m_builder.CreateBitCast(value, llvm::VectorType::get(Type::Byte, 32), "bytes");
-			auto byte = m_builder.CreateExtractElement(bytes, byteNum, "byte");
+			auto safeByteNum = m_builder.CreateZExt(m_builder.CreateTrunc(byteNum, m_builder.getIntNTy(5)), Type::lowPrecision); // Trim index, large values can crash
+			auto byte = m_builder.CreateExtractElement(bytes, safeByteNum, "byte");
 			value = m_builder.CreateZExt(byte, Type::Word);
 
 			auto byteNumValid = m_builder.CreateICmpULT(byteNum, Constant::get(32));
@@ -564,7 +586,7 @@ void Compiler::compileBasicBlock(BasicBlock& _basicBlock, bytes const& _bytecode
 				}
 				else
 				{
-					stack.push(target);
+					_basicBlock.setJumpTarget(target);
 					m_builder.CreateBr(getJumpTableBlock());
 				}
 			}
@@ -580,7 +602,7 @@ void Compiler::compileBasicBlock(BasicBlock& _basicBlock, bytes const& _bytecode
 				}
 				else
 				{
-					stack.push(target);
+					_basicBlock.setJumpTarget(target);
 					m_builder.CreateCondBr(cond, getJumpTableBlock(), _nextBasicBlock);
 				}
 			}
@@ -644,7 +666,7 @@ void Compiler::compileBasicBlock(BasicBlock& _basicBlock, bytes const& _bytecode
 		case Instruction::EXTCODESIZE:
 		{
 			auto addr = stack.pop();
-			auto codeRef = _ext.getExtCode(addr);
+			auto codeRef = _ext.extcode(addr);
 			stack.push(codeRef.size);
 			break;
 		}
@@ -682,7 +704,7 @@ void Compiler::compileBasicBlock(BasicBlock& _basicBlock, bytes const& _bytecode
 			auto srcIdx = stack.pop();
 			auto reqBytes = stack.pop();
 
-			auto codeRef = _ext.getExtCode(addr);
+			auto codeRef = _ext.extcode(addr);
 
 			_memory.copyBytes(codeRef.ptr, codeRef.size, srcIdx, destMemIdx, reqBytes);
 			break;
diff --git a/evmjit/libevmjit/ExecutionEngine.cpp b/evmjit/libevmjit/ExecutionEngine.cpp
index 71142fbeee..ee92a6ba9e 100644
--- a/evmjit/libevmjit/ExecutionEngine.cpp
+++ b/evmjit/libevmjit/ExecutionEngine.cpp
@@ -19,7 +19,12 @@
 #include "Compiler.h"
 #include "Cache.h"
 
-extern "C" void env_sha3(dev::eth::jit::byte const* _begin, uint64_t _size, std::array<dev::eth::jit::byte, 32>* o_hash);
+#if defined(NDEBUG)
+#define DEBUG_ENV_OPTION(name) false
+#else
+#include <cstdlib>
+#define DEBUG_ENV_OPTION(name) (std::getenv(#name) != nullptr)
+#endif
 
 namespace dev
 {
@@ -49,14 +54,17 @@ ReturnCode runEntryFunc(EntryFuncPtr _mainFunc, Runtime* _runtime)
 
 std::string codeHash(bytes const& _code)
 {
-	std::array<byte, 32> binHash;
-	env_sha3(_code.data(), _code.size(), &binHash);
-
-	std::ostringstream os;
-	for (auto i: binHash)
-		os << std::hex << std::setfill('0') << std::setw(2) << (int)(std::make_unsigned<decltype(i)>::type)i;
-
-	return os.str();
+	uint32_t hash = 0;
+	for (auto b : _code)
+	{
+		hash += b;
+		hash += (hash << 10);
+		hash ^= (hash >> 6);
+	}
+	hash += (hash << 3);
+	hash ^= (hash >> 11);
+	hash += (hash << 15);
+	return std::to_string(hash);
 }
 
 }
@@ -64,6 +72,8 @@ std::string codeHash(bytes const& _code)
 ReturnCode ExecutionEngine::run(bytes const& _code, RuntimeData* _data, Env* _env)
 {
 	static std::unique_ptr<llvm::ExecutionEngine> ee;  // TODO: Use Managed Objects from LLVM?
+	static auto debugDumpModule = DEBUG_ENV_OPTION(EVMJIT_DUMP_MODULE);
+	static bool objectCacheEnabled = !DEBUG_ENV_OPTION(EVMJIT_CACHE_OFF);
 
 	auto mainFuncName = codeHash(_code);
 	EntryFuncPtr entryFuncPtr{};
@@ -74,14 +84,14 @@ ReturnCode ExecutionEngine::run(bytes const& _code, RuntimeData* _data, Env* _en
 	}
 	else
 	{
-		bool objectCacheEnabled = true;
 		auto objectCache = objectCacheEnabled ? Cache::getObjectCache() : nullptr;
 		std::unique_ptr<llvm::Module> module;
 		if (objectCache)
 			module = Cache::getObject(mainFuncName);
 		if (!module)
 			module = Compiler({}).compile(_code, mainFuncName);
-		//module->dump();
+		if (debugDumpModule)
+			module->dump();
 		if (!ee)
 		{
 			llvm::InitializeNativeTarget();
@@ -92,7 +102,7 @@ ReturnCode ExecutionEngine::run(bytes const& _code, RuntimeData* _data, Env* _en
 			builder.setUseMCJIT(true);
 			std::unique_ptr<llvm::SectionMemoryManager> memoryManager(new llvm::SectionMemoryManager);
 			builder.setMCJITMemoryManager(memoryManager.get());
-			builder.setOptLevel(llvm::CodeGenOpt::Default);
+			builder.setOptLevel(llvm::CodeGenOpt::None);
 
 			auto triple = llvm::Triple(llvm::sys::getProcessTriple());
 			if (triple.getOS() == llvm::Triple::OSType::Win32)
@@ -126,7 +136,10 @@ ReturnCode ExecutionEngine::run(bytes const& _code, RuntimeData* _data, Env* _en
 
 	auto returnCode = runEntryFunc(entryFuncPtr, &runtime);
 	if (returnCode == ReturnCode::Return)
-		this->returnData = runtime.getReturnData();
+	{
+		returnData = runtime.getReturnData();     // Save reference to return data
+		std::swap(m_memory, runtime.getMemory()); // Take ownership of memory
+	}
 
 	auto executionEndTime = std::chrono::high_resolution_clock::now();
 	clog(JIT) << " + " << std::chrono::duration_cast<std::chrono::milliseconds>(executionEndTime - executionStartTime).count() << " ms\n";
diff --git a/evmjit/libevmjit/ExecutionEngine.h b/evmjit/libevmjit/ExecutionEngine.h
index 559701bba7..52e3b29fa6 100644
--- a/evmjit/libevmjit/ExecutionEngine.h
+++ b/evmjit/libevmjit/ExecutionEngine.h
@@ -18,7 +18,13 @@ public:
 
 	ReturnCode run(bytes const& _code, RuntimeData* _data, Env* _env);
 
-	bytes returnData;
+	/// Reference to returned data (RETURN opcode used)
+	bytes_ref returnData;
+
+private:
+	/// After execution, if RETURN used, memory is moved there
+	/// to allow client copy the returned data
+	bytes m_memory;
 };
 
 }
diff --git a/evmjit/libevmjit/Ext.cpp b/evmjit/libevmjit/Ext.cpp
index f0767d9e03..a37a6fe995 100644
--- a/evmjit/libevmjit/Ext.cpp
+++ b/evmjit/libevmjit/Ext.cpp
@@ -5,9 +5,6 @@
 #include <llvm/IR/TypeBuilder.h>
 #include <llvm/IR/IntrinsicInst.h>
 
-//#include <libdevcrypto/SHA3.h>
-//#include <libevm/FeeStructure.h>
-
 #include "RuntimeManager.h"
 #include "Memory.h"
 #include "Type.h"
@@ -22,10 +19,10 @@ namespace jit
 
 Ext::Ext(RuntimeManager& _runtimeManager, Memory& _memoryMan):
 	RuntimeHelper(_runtimeManager),
-	m_memoryMan(_memoryMan),
-	m_funcs({}),  // The only std::array initialization that works in both Visual Studio & GCC
-	m_argAllocas({})
+	m_memoryMan(_memoryMan)
 {
+	m_funcs = decltype(m_funcs)();
+	m_argAllocas = decltype(m_argAllocas)();
 	m_size = m_builder.CreateAlloca(Type::Size, nullptr, "env.size");
 }
 
@@ -48,7 +45,7 @@ std::array<FuncDesc, sizeOf<EnvFunc>::value> const& getEnvFuncDescs()
 		FuncDesc{"env_call", getFunctionType(Type::Bool, {Type::EnvPtr, Type::WordPtr, Type::WordPtr, Type::WordPtr, Type::BytePtr, Type::Size, Type::BytePtr, Type::Size, Type::WordPtr})},
 		FuncDesc{"env_log", getFunctionType(Type::Void, {Type::EnvPtr, Type::BytePtr, Type::Size, Type::WordPtr, Type::WordPtr, Type::WordPtr, Type::WordPtr})},
 		FuncDesc{"env_blockhash", getFunctionType(Type::Void, {Type::EnvPtr, Type::WordPtr, Type::WordPtr})},
-		FuncDesc{"env_getExtCode", getFunctionType(Type::BytePtr, {Type::EnvPtr, Type::WordPtr, Type::Size->getPointerTo()})},
+		FuncDesc{"env_extcode", getFunctionType(Type::BytePtr, {Type::EnvPtr, Type::WordPtr, Type::Size->getPointerTo()})},
 		FuncDesc{"ext_calldataload", getFunctionType(Type::Void, {Type::RuntimeDataPtr, Type::WordPtr, Type::WordPtr})},
 	}};
 
@@ -71,7 +68,6 @@ llvm::Value* Ext::getArgAlloca()
 		getBuilder().SetInsertPoint(getMainFunction()->front().getFirstNonPHI());
 		a = getBuilder().CreateAlloca(Type::Word, nullptr, "arg");
 	}
-		
 	return a;
 }
 
@@ -166,10 +162,10 @@ llvm::Value* Ext::sha3(llvm::Value* _inOff, llvm::Value* _inSize)
 	return hash;
 }
 
-MemoryRef Ext::getExtCode(llvm::Value* _addr)
+MemoryRef Ext::extcode(llvm::Value* _addr)
 {
 	auto addr = Endianness::toBE(m_builder, _addr);
-	auto code = createCall(EnvFunc::getExtCode, {getRuntimeManager().getEnvPtr(), byPtr(addr), m_size});
+	auto code = createCall(EnvFunc::extcode, {getRuntimeManager().getEnvPtr(), byPtr(addr), m_size});
 	auto codeSize = m_builder.CreateLoad(m_size);
 	auto codeSize256 = m_builder.CreateZExt(codeSize, Type::Word);
 	return {code, codeSize256};
diff --git a/evmjit/libevmjit/Ext.h b/evmjit/libevmjit/Ext.h
index 86a8a6190d..2601d32abc 100644
--- a/evmjit/libevmjit/Ext.h
+++ b/evmjit/libevmjit/Ext.h
@@ -34,7 +34,7 @@ enum class EnvFunc
 	call,
 	log,
 	blockhash,
-	getExtCode,
+	extcode,
 	calldataload,  // Helper function, not client Env interface
 
 	_size
@@ -55,7 +55,7 @@ public:
 	llvm::Value* blockhash(llvm::Value* _number);
 
 	llvm::Value* sha3(llvm::Value* _inOff, llvm::Value* _inSize);
-	MemoryRef getExtCode(llvm::Value* _addr);
+	MemoryRef extcode(llvm::Value* _addr);
 
 	void log(llvm::Value* _memIdx, llvm::Value* _numBytes, std::array<llvm::Value*,4> const& _topics);
 
diff --git a/evmjit/libevmjit/Runtime.cpp b/evmjit/libevmjit/Runtime.cpp
index 911dc469d4..989c053dcc 100644
--- a/evmjit/libevmjit/Runtime.cpp
+++ b/evmjit/libevmjit/Runtime.cpp
@@ -18,18 +18,18 @@ Runtime::Runtime(RuntimeData* _data, Env* _env) :
 	m_currJmpBuf(m_jmpBuf)
 {}
 
-bytes Runtime::getReturnData() const	// FIXME: Reconsider returning by copy
+bytes_ref Runtime::getReturnData() const
 {
 	// TODO: Handle large indexes
-	auto offset = static_cast<size_t>(llvm2eth(m_data.elems[RuntimeData::ReturnDataOffset]));
-	auto size = static_cast<size_t>(llvm2eth(m_data.elems[RuntimeData::ReturnDataSize]));
+	auto offset = static_cast<size_t>(m_data.elems[RuntimeData::ReturnDataOffset].a);
+	auto size = static_cast<size_t>(m_data.elems[RuntimeData::ReturnDataSize].a);
 
 	assert(offset + size <= m_memory.size() || size == 0);
 	if (offset + size > m_memory.size())
 		return {};
 
-	auto dataBeg = m_memory.begin() + offset;
-	return {dataBeg, dataBeg + size};
+	auto dataBeg = m_memory.data() + offset;
+	return bytes_ref{dataBeg, size};
 }
 
 }
diff --git a/evmjit/libevmjit/Runtime.h b/evmjit/libevmjit/Runtime.h
index 8cc5b79686..df1bde7fd7 100644
--- a/evmjit/libevmjit/Runtime.h
+++ b/evmjit/libevmjit/Runtime.h
@@ -2,15 +2,8 @@
 #pragma once
 
 #include <csetjmp>
-#include <vector>
-
-#include "Instruction.h"
-#include "CompilerHelper.h"
-#include "Utils.h"
-#include "Type.h"
 #include "RuntimeData.h"
 
-
 #ifdef _MSC_VER
 	#define EXPORT __declspec(dllexport)
 #else
@@ -34,13 +27,13 @@ public:
 	Runtime(RuntimeData* _data, Env* _env);
 
 	Runtime(const Runtime&) = delete;
-	void operator=(const Runtime&) = delete;
+	Runtime& operator=(const Runtime&) = delete;
 
 	StackImpl& getStack() { return m_stack; }
 	MemoryImpl& getMemory() { return m_memory; }
 	Env* getEnvPtr() { return &m_env; }
 
-	bytes getReturnData() const;
+	bytes_ref getReturnData() const;
 	jmp_buf_ref getJmpBuf() { return m_jmpBuf; }
 
 private:
diff --git a/evmjit/libevmjit/RuntimeData.h b/evmjit/libevmjit/RuntimeData.h
index bb52f78648..a71cd468b9 100644
--- a/evmjit/libevmjit/RuntimeData.h
+++ b/evmjit/libevmjit/RuntimeData.h
@@ -38,9 +38,6 @@ struct RuntimeData
 	i256 elems[_size] = {};
 	byte const* callData = nullptr;
 	byte const* code = nullptr;
-
-	void set(Index _index, u256 _value) { elems[_index] = eth2llvm(_value); }
-	u256 get(Index _index) { return llvm2eth(elems[_index]); }
 };
 
 /// VM Environment (ExtVM) opaque type
diff --git a/evmjit/libevmjit/Utils.cpp b/evmjit/libevmjit/Utils.cpp
index 0fd9c0e41c..5f7f75bfd4 100644
--- a/evmjit/libevmjit/Utils.cpp
+++ b/evmjit/libevmjit/Utils.cpp
@@ -8,32 +8,6 @@ namespace eth
 namespace jit
 {
 
-u256 llvm2eth(i256 _i)
-{
-	u256 u = 0;
-	u |= _i.d;
-	u <<= 64;
-	u |= _i.c;
-	u <<= 64;
-	u |= _i.b;
-	u <<= 64;
-	u |= _i.a;
-	return u;
-}
-
-i256 eth2llvm(u256 _u)
-{
-	i256 i;
-	u256 mask = 0xFFFFFFFFFFFFFFFF;
-	i.a = static_cast<uint64_t>(_u & mask);
-	_u >>= 64;
-	i.b = static_cast<uint64_t>(_u & mask);
-	_u >>= 64;
-	i.c = static_cast<uint64_t>(_u & mask);
-	_u >>= 64;
-	i.d = static_cast<uint64_t>(_u & mask);
-	return i;
-}
 
 }
 }
diff --git a/evmjit/libevmjit/Utils.h b/evmjit/libevmjit/Utils.h
index f672365c6b..1e67056676 100644
--- a/evmjit/libevmjit/Utils.h
+++ b/evmjit/libevmjit/Utils.h
@@ -14,9 +14,6 @@ struct JIT: public NoteChannel  { static const char* name() { return "JIT"; } };
 //#define clog(CHANNEL) std::cerr
 #define clog(CHANNEL) std::ostream(nullptr)
 
-u256 llvm2eth(i256);
-i256 eth2llvm(u256);
-
 }
 }
 }
diff --git a/evmjit/libevmjit/interface.cpp b/evmjit/libevmjit/interface.cpp
index eef92d00fd..5d2b97c2d2 100644
--- a/evmjit/libevmjit/interface.cpp
+++ b/evmjit/libevmjit/interface.cpp
@@ -1,5 +1,5 @@
 #include "interface.h"
-#include <cstdio>
+#include <cstring>
 #include "ExecutionEngine.h"
 
 extern "C"
@@ -20,12 +20,12 @@ evmjit_result evmjit_run(void* _data, void* _env)
 
 	auto returnCode = engine.run(bytecode, data, static_cast<Env*>(_env));
 	evmjit_result result = {static_cast<int32_t>(returnCode), 0, nullptr};
-	if (returnCode == ReturnCode::Return && !engine.returnData.empty())
+	if (returnCode == ReturnCode::Return && std::get<0>(engine.returnData))
 	{
 		// TODO: Optimized returning data. Allocating memory on client side by callback function might be a good idea
-		result.returnDataSize = engine.returnData.size();
+		result.returnDataSize = std::get<1>(engine.returnData);
 		result.returnData = std::malloc(result.returnDataSize);
-		std::memcpy(result.returnData, engine.returnData.data(), result.returnDataSize);
+		std::memcpy(result.returnData, std::get<0>(engine.returnData), result.returnDataSize);
 	}
 
 	return result;