diff --git a/libevmjit/Compiler.cpp b/libevmjit/Compiler.cpp
index 593820b8cb..939c4a275a 100644
--- a/libevmjit/Compiler.cpp
+++ b/libevmjit/Compiler.cpp
@@ -504,6 +504,36 @@ void Compiler::compileBasicBlock(BasicBlock& basicBlock, bytesConstRef bytecode,
 			break;
 		}
 
+		case Instruction::SIGNEXTEND:
+		{
+			auto idx = stack.pop();
+			auto word = stack.pop();
+
+			auto k32_ = m_builder.CreateTrunc(idx, m_builder.getIntNTy(5), "k_32");
+			auto k32 = m_builder.CreateZExt(k32_, Type::i256);
+			auto k32x8 = m_builder.CreateMul(k32, Constant::get(8), "kx8");
+
+			// test for b >> (k * 8 + 7)
+			auto bitpos = m_builder.CreateAdd(k32x8, Constant::get(7), "bitpos");
+			auto bitval = m_builder.CreateLShr(word, bitpos, "bitval");
+			auto bittest = m_builder.CreateTrunc(bitval, m_builder.getInt1Ty(), "bittest");
+
+			auto mask_ = m_builder.CreateShl(Constant::get(1), bitpos);
+			auto mask = m_builder.CreateSub(mask_, Constant::get(1), "mask");
+
+			auto negmask = m_builder.CreateXor(mask, llvm::ConstantInt::getAllOnesValue(Type::i256), "negmask");
+			auto val1 = m_builder.CreateOr(word, negmask);
+			auto val0 = m_builder.CreateAnd(word, mask);
+
+			auto kInRange = m_builder.CreateICmpULE(idx, llvm::ConstantInt::get(Type::i256, 30));
+			auto result = m_builder.CreateSelect(kInRange,
+			                                     m_builder.CreateSelect(bittest, val1, val0),
+			                                     word);
+			stack.push(result);
+
+			break;
+		}
+
 		case Instruction::SHA3:
 		{
 			auto inOff = stack.pop();
diff --git a/libevmjit/Ext.cpp b/libevmjit/Ext.cpp
index 09b3507636..0fe795a1fe 100644
--- a/libevmjit/Ext.cpp
+++ b/libevmjit/Ext.cpp
@@ -26,14 +26,13 @@ inline u256 fromAddress(Address _a)
 }
 
 Ext::Ext(RuntimeManager& _runtimeManager):
-	RuntimeHelper(_runtimeManager)
+	RuntimeHelper(_runtimeManager),
+	m_data()
 {
 	auto&& ctx = m_builder.getContext();
 	auto module = getModule();
 
 	auto i256Ty = m_builder.getIntNTy(256);
-	auto i256PtrTy = i256Ty->getPointerTo();
-	auto i8PtrTy = m_builder.getInt8PtrTy();
 
 	m_args[0] = m_builder.CreateAlloca(i256Ty, nullptr, "ext.index");
 	m_args[1] = m_builder.CreateAlloca(i256Ty, nullptr, "ext.value");
@@ -266,7 +265,7 @@ extern "C"
 		*_ret = *reinterpret_cast<i256*>(&hash);
 	}
 
-	EXPORT void ext_exp(Runtime* _rt, i256* _left, i256* _right, i256* _ret)
+	EXPORT void ext_exp(Runtime*, i256* _left, i256* _right, i256* _ret)
 	{
 		bigint left = llvm2eth(*_left);
 		bigint right = llvm2eth(*_right);
diff --git a/libevmjit/Memory.cpp b/libevmjit/Memory.cpp
index 63e97efc60..86c6e8e07c 100644
--- a/libevmjit/Memory.cpp
+++ b/libevmjit/Memory.cpp
@@ -89,7 +89,7 @@ llvm::Function* Memory::createRequireFunc(GasMeter& _gasMeter, RuntimeManager& _
 	return func;
 }
 
-llvm::Function* Memory::createFunc(bool _isStore, llvm::Type* _valueType, GasMeter& _gasMeter)
+llvm::Function* Memory::createFunc(bool _isStore, llvm::Type* _valueType, GasMeter&)
 {
 	auto isWord = _valueType == Type::i256;
 
@@ -228,28 +228,4 @@ extern "C"
 		return memory.data();
 	}
 
-	EXPORT void evmccrt_memory_dump(uint64_t _begin, uint64_t _end)
-	{
-		//if (_end == 0)
-		//  _end = Runtime::getMemory().size();
-
-		//std::cerr << "MEMORY: active size: " << std::dec
-		//        << Runtime::getMemory().size() / 32 << " words\n";
-		//std::cerr << "MEMORY: dump from " << std::dec
-		//        << _begin << " to " << _end << ":";
-		//if (_end <= _begin)
-		//  return;
-
-		//_begin = _begin / 16 * 16;
-		//for (size_t i = _begin; i < _end; i++)
-		//{
-		//  if ((i - _begin) % 16 == 0)
-		//      std::cerr << '\n' << std::dec << i << ":  ";
-
-		//  auto b = Runtime::getMemory()[i];
-		//  std::cerr << std::hex << std::setw(2) << static_cast<int>(b) << ' ';
-		//}
-		//std::cerr << std::endl;
-	}
-
 }   // extern "C"
diff --git a/libevmjit/VM.cpp b/libevmjit/VM.cpp
index c0a8c8605c..b42b094992 100644
--- a/libevmjit/VM.cpp
+++ b/libevmjit/VM.cpp
@@ -31,6 +31,8 @@ bytesConstRef VM::go(ExtVMFace& _ext, OnOpFunc const&, uint64_t)
 		BOOST_THROW_EXCEPTION(StackTooSmall(1, 0));
 	case ReturnCode::BadInstruction:
 		BOOST_THROW_EXCEPTION(BadInstruction());
+	default:
+		break;
 	}
 
 	m_output = std::move(engine.returnData);