diff --git a/libsolidity/codegen/ContractCompiler.cpp b/libsolidity/codegen/ContractCompiler.cpp
index 8320d23d5..b10882749 100644
--- a/libsolidity/codegen/ContractCompiler.cpp
+++ b/libsolidity/codegen/ContractCompiler.cpp
@@ -177,6 +177,7 @@ size_t ContractCompiler::deployLibrary(ContractDefinition const& _contract)
 	solAssert(m_context.runtimeSub() != size_t(-1), "Runtime sub not registered");
 	m_context.pushSubroutineSize(m_context.runtimeSub());
 	m_context.pushSubroutineOffset(m_context.runtimeSub());
+	// This code replaces the address added by appendDeployTimeAddress().
 	m_context.appendInlineAssembly(R"(
 	{
 		// If code starts at 11, an mstore(0) writes to the full PUSH20 plus data
@@ -184,8 +185,7 @@ size_t ContractCompiler::deployLibrary(ContractDefinition const& _contract)
 		let codepos := 11
 		codecopy(codepos, subOffset, subSize)
 		// Check that the first opcode is a PUSH20
-		switch eq(0x73, byte(0, mload(codepos)))
-		case 0 { invalid() }
+		if iszero(eq(0x73, byte(0, mload(codepos)))) { invalid() }
 		mstore(0, address())
 		mstore8(codepos, 0x73)
 		return(codepos, subSize)