diff --git a/docs/contributing.rst b/docs/contributing.rst
index 8a83ca553..6fe96be48 100644
--- a/docs/contributing.rst
+++ b/docs/contributing.rst
@@ -92,7 +92,7 @@ To run a subset of tests, filters can be used:
 ``soltest -t TestSuite/TestName -- --ipcpath /tmp/testeth/geth.ipc --testpath ./test``,
 where ``TestName`` can be a wildcard ``*``.
 
-Alternatively, there is a testing script at ``scripts/test.sh`` which executes all tests and runs
+Alternatively, there is a testing script at ``scripts/tests.sh`` which executes all tests and runs
 ``cpp-ethereum`` automatically if it is in the path (but does not download it).
 
 Travis CI even runs some additional tests (including ``solc-js`` and testing third party Solidity frameworks) that require compiling the Emscripten target.
diff --git a/libsolidity/analysis/TypeChecker.cpp b/libsolidity/analysis/TypeChecker.cpp
index e023dc38e..13294476f 100644
--- a/libsolidity/analysis/TypeChecker.cpp
+++ b/libsolidity/analysis/TypeChecker.cpp
@@ -535,7 +535,7 @@ TypePointers TypeChecker::typeCheckABIDecodeAndRetrieveReturnType(FunctionCall c
 			toString(arguments.size()) +
 			" were provided."
 		);
-	if (arguments.size() >= 1 && !type(*arguments.front())->isImplicitlyConvertibleTo(ArrayType(DataLocation::Memory)))
+	if (arguments.size() >= 1 && !type(*arguments.front())->isImplicitlyConvertibleTo(ArrayType::bytesMemory()))
 		m_errorReporter.typeError(
 			arguments.front()->location(),
 			"Invalid type for argument in function call. "
@@ -2131,7 +2131,7 @@ bool TypeChecker::visit(MemberAccess const& _memberAccess)
 				"after argument-dependent lookup in " + exprType->toString() +
 				(memberName == "value" ? " - did you forget the \"payable\" modifier?" : ".");
 		if (exprType->category() == Type::Category::Contract)
-			for (auto const& addressMember: AddressType(StateMutability::Payable).nativeMembers(nullptr))
+			for (auto const& addressMember: AddressType::addressPayable().nativeMembers(nullptr))
 				if (addressMember.name == memberName)
 				{
 					Identifier const* var = dynamic_cast<Identifier const*>(&_memberAccess.expression());
diff --git a/libsolidity/ast/Types.h b/libsolidity/ast/Types.h
index a2d18b0ae..65a70019c 100644
--- a/libsolidity/ast/Types.h
+++ b/libsolidity/ast/Types.h
@@ -319,6 +319,9 @@ protected:
 class AddressType: public Type
 {
 public:
+    static AddressType& address() { static std::shared_ptr<AddressType> addr(std::make_shared<AddressType>(StateMutability::NonPayable)); return *addr; }
+    static AddressType& addressPayable() { static std::shared_ptr<AddressType> addr(std::make_shared<AddressType>(StateMutability::Payable)); return *addr; }
+
 	virtual Category category() const override { return Category::Address; }
 
 	explicit AddressType(StateMutability _stateMutability);
@@ -361,6 +364,7 @@ public:
 	{
 		Unsigned, Signed
 	};
+
 	virtual Category category() const override { return Category::Integer; }
 
 	explicit IntegerType(unsigned _bits, Modifier _modifier = Modifier::Unsigned);
@@ -661,6 +665,9 @@ protected:
 class ArrayType: public ReferenceType
 {
 public:
+	static ArrayType& bytesMemory() { static std::shared_ptr<ArrayType> addr(std::make_shared<ArrayType>(DataLocation::Memory)); return *addr; }
+	static ArrayType& stringMemory() { static std::shared_ptr<ArrayType> addr(std::make_shared<ArrayType>(DataLocation::Memory, true)); return *addr; }
+
 	virtual Category category() const override { return Category::Array; }
 
 	/// Constructor for a byte array ("bytes") and string.
diff --git a/libsolidity/codegen/ExpressionCompiler.cpp b/libsolidity/codegen/ExpressionCompiler.cpp
index bd863e058..8645f653c 100644
--- a/libsolidity/codegen/ExpressionCompiler.cpp
+++ b/libsolidity/codegen/ExpressionCompiler.cpp
@@ -710,9 +710,9 @@ bool ExpressionCompiler::visit(FunctionCall const& _functionCall)
 			arguments.front()->accept(*this);
 			// Optimization: If type is bytes or string, then do not encode,
 			// but directly compute keccak256 on memory.
-			if (*argType == ArrayType(DataLocation::Memory) || *argType == ArrayType(DataLocation::Memory, true))
+			if (*argType == ArrayType::bytesMemory() || *argType == ArrayType::stringMemory())
 			{
-				ArrayUtils(m_context).retrieveLength(ArrayType(DataLocation::Memory));
+				ArrayUtils(m_context).retrieveLength(ArrayType::bytesMemory());
 				m_context << Instruction::SWAP1 << u256(0x20) << Instruction::ADD;
 			}
 			else
@@ -1086,7 +1086,7 @@ bool ExpressionCompiler::visit(FunctionCall const& _functionCall)
 				utils().abiDecode(targetTypes, false);
 			else
 			{
-				utils().convertType(*firstArgType, ArrayType(DataLocation::Memory));
+				utils().convertType(*firstArgType, ArrayType::bytesMemory());
 				m_context << Instruction::DUP1 << u256(32) << Instruction::ADD;
 				m_context << Instruction::SWAP1 << Instruction::MLOAD;
 				// stack now: <mem_pos> <length>
@@ -1259,7 +1259,7 @@ bool ExpressionCompiler::visit(MemberAccess const& _memberAccess)
 				identifier = FunctionType(*function).externalIdentifier();
 			else
 				solAssert(false, "Contract member is neither variable nor function.");
-			utils().convertType(type, AddressType(type.isPayable() ? StateMutability::Payable : StateMutability::NonPayable), true);
+			utils().convertType(type, type.isPayable() ? AddressType::addressPayable() : AddressType::address(), true);
 			m_context << identifier;
 		}
 		else
@@ -1277,7 +1277,7 @@ bool ExpressionCompiler::visit(MemberAccess const& _memberAccess)
 		{
 			utils().convertType(
 				*_memberAccess.expression().annotation().type,
-				AddressType(StateMutability::NonPayable),
+				AddressType::address(),
 				true
 			);
 			m_context << Instruction::BALANCE;
@@ -1294,7 +1294,7 @@ bool ExpressionCompiler::visit(MemberAccess const& _memberAccess)
 		else if ((set<string>{"call", "callcode", "delegatecall", "staticcall"}).count(member))
 			utils().convertType(
 				*_memberAccess.expression().annotation().type,
-				AddressType(StateMutability::NonPayable),
+				AddressType::address(),
 				true
 			);
 		else