diff --git a/libsolidity/interface/CompilerStack.cpp b/libsolidity/interface/CompilerStack.cpp
index da2e222b5..c1adf5e78 100644
--- a/libsolidity/interface/CompilerStack.cpp
+++ b/libsolidity/interface/CompilerStack.cpp
@@ -687,13 +687,15 @@ bool CompilerStack::compile(State _stopAfter)
 
 		m_contracts[evmAssemblyJsonSource].evmAssembly = make_shared<evmasm::Assembly>(evmAssemblyJsonSource);
 		m_contracts[evmAssemblyJsonSource].evmAssembly->loadFromAssemblyJSON(m_evmAssemblyJson[evmAssemblyJsonSource]);
-//		m_contracts[evmAssemblyJsonSource].evmAssembly->optimise(optimiserSettings);
+		if (m_optimiserSettings.enabled)
+			m_contracts[evmAssemblyJsonSource].evmAssembly->optimise(optimiserSettings);
 		m_contracts[evmAssemblyJsonSource].object = m_contracts[evmAssemblyJsonSource].evmAssembly->assemble();
 
 		m_contracts[evmAssemblyJsonSource].evmRuntimeAssembly = make_shared<evmasm::Assembly>(evmAssemblyJsonSource);
 		m_contracts[evmAssemblyJsonSource].evmRuntimeAssembly->setSources(m_contracts[evmAssemblyJsonSource].evmAssembly->sources());
 		m_contracts[evmAssemblyJsonSource].evmRuntimeAssembly->loadFromAssemblyJSON(m_evmAssemblyJson[evmAssemblyJsonSource][".data"]["0"], false);
-//		m_contracts[evmAssemblyJsonSource].evmRuntimeAssembly->optimise(optimiserSettings);
+		if (m_optimiserSettings.enabled)
+			m_contracts[evmAssemblyJsonSource].evmRuntimeAssembly->optimise(optimiserSettings);
 		m_contracts[evmAssemblyJsonSource].runtimeObject = m_contracts[evmAssemblyJsonSource].evmRuntimeAssembly->assemble();
 	}
 	else
diff --git a/libsolidity/interface/OptimiserSettings.h b/libsolidity/interface/OptimiserSettings.h
index 5317acee4..528730eca 100644
--- a/libsolidity/interface/OptimiserSettings.h
+++ b/libsolidity/interface/OptimiserSettings.h
@@ -121,6 +121,8 @@ struct OptimiserSettings
 			expectedExecutionsPerDeployment == _other.expectedExecutionsPerDeployment;
 	}
 
+	/// Optimizer enabled.
+	bool enabled = false;
 	/// Move literals to the right of commutative binary operators during code generation.
 	/// This helps exploiting associativity.
 	bool runOrderLiterals = false;