diff --git a/libsolidity/analysis/NameAndTypeResolver.cpp b/libsolidity/analysis/NameAndTypeResolver.cpp
index 2742dcf22f96..7e2a05b49183 100644
--- a/libsolidity/analysis/NameAndTypeResolver.cpp
+++ b/libsolidity/analysis/NameAndTypeResolver.cpp
@@ -232,6 +232,19 @@ vector<Declaration const*> NameAndTypeResolver::cleanedDeclarations(
 	return uniqueFunctions;
 }
 
+void NameAndTypeResolver::warnVariablesNamedLikeInstructions(void)
+{
+	auto declarations = nameFromCurrentScope("returndatasize");
+	for (Declaration const* const declaration : declarations)
+	{
+		solAssert(!!declaration, "");
+		m_errorReporter.warning(
+			declaration->location(),
+			"Variable is shadowed in an inline assembly by an insturction of the same name"
+		);
+	}
+}
+
 bool NameAndTypeResolver::resolveNamesAndTypesInternal(ASTNode& _node, bool _resolveInsideCode)
 {
 	if (ContractDefinition* contract = dynamic_cast<ContractDefinition*>(&_node))
diff --git a/libsolidity/analysis/NameAndTypeResolver.h b/libsolidity/analysis/NameAndTypeResolver.h
index 0441867d5d3c..c61d13eea269 100644
--- a/libsolidity/analysis/NameAndTypeResolver.h
+++ b/libsolidity/analysis/NameAndTypeResolver.h
@@ -90,6 +90,9 @@ class NameAndTypeResolver: private boost::noncopyable
 		std::vector<Declaration const*> const& _declarations
 	);
 
+	/// Generate and store warnings about variables that are named like instructions.
+	void warnVariablesNamedLikeInstructions(void);
+
 private:
 	/// Internal version of @a resolveNamesAndTypes (called from there) throws exceptions on fatal errors.
 	bool resolveNamesAndTypesInternal(ASTNode& _node, bool _resolveInsideCode = true);
diff --git a/libsolidity/analysis/ReferencesResolver.cpp b/libsolidity/analysis/ReferencesResolver.cpp
index b70b0f0e52fd..9e5f786fdf79 100644
--- a/libsolidity/analysis/ReferencesResolver.cpp
+++ b/libsolidity/analysis/ReferencesResolver.cpp
@@ -162,6 +162,8 @@ void ReferencesResolver::endVisit(ArrayTypeName const& _typeName)
 
 bool ReferencesResolver::visit(InlineAssembly const& _inlineAssembly)
 {
+	m_resolver.warnVariablesNamedLikeInstructions();
+
 	// Errors created in this stage are completely ignored because we do not yet know
 	// the type and size of external identifiers, which would result in false errors.
 	// The only purpose of this step is to fill the inline assembly annotation with
diff --git a/test/libsolidity/SolidityNameAndTypeResolution.cpp b/test/libsolidity/SolidityNameAndTypeResolution.cpp
index f2c056995fce..d76d55acbdb0 100644
--- a/test/libsolidity/SolidityNameAndTypeResolution.cpp
+++ b/test/libsolidity/SolidityNameAndTypeResolution.cpp
@@ -5744,7 +5744,7 @@ BOOST_AUTO_TEST_CASE(returndatacopy_as_variable)
 	char const* text = R"(
 		contract c { function f() { uint returndatasize; assembly { returndatasize }}}
 	)";
-	CHECK_WARNING_ALLOW_MULTI(text, "shadowed by an insturction of the same name");
+	CHECK_WARNING_ALLOW_MULTI(text, "Variable is shadowed in an inline assembly by an insturction of the same name");
 }