diff --git a/Changelog.md b/Changelog.md
index 86787337e..763312b52 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -3,6 +3,7 @@
 Bugfixes:
  * Code generator: Defensively pad allocation of creationCode and runtimeCode to multiples of 32 bytes.
  * Parser: Disallow empty import statements.
+ * Type Checker: Dissallow mappings with data locations other than 'storage'
  * Type system: Properly report packed encoded size for arrays and structs (mostly unused until now).
 
 
diff --git a/libsolidity/analysis/TypeChecker.cpp b/libsolidity/analysis/TypeChecker.cpp
index 6d887c454..b5b7d9152 100644
--- a/libsolidity/analysis/TypeChecker.cpp
+++ b/libsolidity/analysis/TypeChecker.cpp
@@ -334,10 +334,17 @@ bool TypeChecker::visit(FunctionDefinition const& _function)
 	auto checkArgumentAndReturnParameter = [&](VariableDeclaration const& var) {
 		if (type(var)->category() == Type::Category::Mapping)
 		{
-			if (!type(var)->dataStoredIn(DataLocation::Storage))
-				m_errorReporter.typeError(var.location(), "Mapping types can only have a data location of \"storage\"." );
-			else if (!isLibraryFunction && _function.isPublic())
-				m_errorReporter.typeError(var.location(), "Mapping types for parameters or return variables can only be used in internal or library functions.");
+			if (var.referenceLocation() != VariableDeclaration::Location::Storage)
+			{
+				if (!isLibraryFunction && _function.isPublic())
+					m_errorReporter.typeError(var.location(), "Mapping types can only have a data location of \"storage\" and thus only be parameters or return variables for internal or library functions.");
+				else
+					m_errorReporter.typeError(var.location(), "Mapping types can only have a data location of \"storage\"." );
+			}
+			else
+			{
+				solAssert(isLibraryFunction || !_function.isPublic(), "Mapping types for parameters or return variables can only be used in internal or library functions.");
+			}
 		}
 		else
 		{
diff --git a/test/libsolidity/syntaxTests/types/mapping/mapping_data_location_function_param_external.sol b/test/libsolidity/syntaxTests/types/mapping/mapping_data_location_function_param_external.sol
index fa3757fa6..d4a7b4599 100644
--- a/test/libsolidity/syntaxTests/types/mapping/mapping_data_location_function_param_external.sol
+++ b/test/libsolidity/syntaxTests/types/mapping/mapping_data_location_function_param_external.sol
@@ -2,5 +2,5 @@ contract c {
     function f1(mapping(uint => uint) calldata) pure external returns (mapping(uint => uint) memory) {}
 }
 // ----
-// TypeError: (29-59): Mapping types for parameters or return variables can only be used in internal or library functions.
-// TypeError: (84-112): Mapping types for parameters or return variables can only be used in internal or library functions.
+// TypeError: (29-59): Mapping types can only have a data location of "storage" and thus only be parameters or return variables for internal or library functions.
+// TypeError: (84-112): Mapping types can only have a data location of "storage" and thus only be parameters or return variables for internal or library functions.
diff --git a/test/libsolidity/syntaxTests/types/mapping/mapping_data_location_function_param_internal.sol b/test/libsolidity/syntaxTests/types/mapping/mapping_data_location_function_param_internal.sol
index 17f2f7128..58c105e86 100644
--- a/test/libsolidity/syntaxTests/types/mapping/mapping_data_location_function_param_internal.sol
+++ b/test/libsolidity/syntaxTests/types/mapping/mapping_data_location_function_param_internal.sol
@@ -1,4 +1,6 @@
 contract c {
-    function f4(mapping(uint => uint) memory) pure internal {}
+    function f4(mapping(uint => uint) storage) pure internal {}
+    function f5(mapping(uint => uint) memory) pure internal {}
 }
 // ----
+// TypeError: (93-121): Mapping types can only have a data location of "storage".
diff --git a/test/libsolidity/syntaxTests/types/mapping/mapping_data_location_function_param_public.sol b/test/libsolidity/syntaxTests/types/mapping/mapping_data_location_function_param_public.sol
index 8c73b5ae9..04932d48a 100644
--- a/test/libsolidity/syntaxTests/types/mapping/mapping_data_location_function_param_public.sol
+++ b/test/libsolidity/syntaxTests/types/mapping/mapping_data_location_function_param_public.sol
@@ -2,4 +2,4 @@ contract c {
     function f3(mapping(uint => uint) memory) view public {}
 }
 // ----
-// TypeError: (29-57): Mapping types for parameters or return variables can only be used in internal or library functions.
+// TypeError: (29-57): Mapping types can only have a data location of "storage" and thus only be parameters or return variables for internal or library functions.
diff --git a/test/libsolidity/syntaxTests/types/mapping/mapping_return_public_memory.sol b/test/libsolidity/syntaxTests/types/mapping/mapping_return_public_memory.sol
index 7378324a7..cf0c67429 100644
--- a/test/libsolidity/syntaxTests/types/mapping/mapping_return_public_memory.sol
+++ b/test/libsolidity/syntaxTests/types/mapping/mapping_return_public_memory.sol
@@ -3,4 +3,4 @@ contract C {
     }
 }
 // ----
-// TypeError: (51-79): Mapping types for parameters or return variables can only be used in internal or library functions.
+// TypeError: (51-79): Mapping types can only have a data location of "storage" and thus only be parameters or return variables for internal or library functions.