diff --git a/libsolidity/analysis/TypeChecker.cpp b/libsolidity/analysis/TypeChecker.cpp
index 1bcfdcdc8..54c37e923 100644
--- a/libsolidity/analysis/TypeChecker.cpp
+++ b/libsolidity/analysis/TypeChecker.cpp
@@ -583,13 +583,18 @@ bool TypeChecker::visit(VariableDeclaration const& _variable)
 
 	if (auto referenceType = dynamic_cast<ReferenceType const*>(varType))
 	{
-		auto result = referenceType->validForLocation(referenceType->location());
+		BoolResult result = referenceType->validForLocation(referenceType->location());
 		if (result)
 		{
 			bool isLibraryStorageParameter = (_variable.isLibraryFunctionParameter() && referenceType->location() == DataLocation::Storage);
 			bool callDataCheckRequired = ((_variable.isConstructorParameter() || _variable.isPublicCallableParameter()) && !isLibraryStorageParameter);
 			if (callDataCheckRequired)
-				result = referenceType->validForLocation(DataLocation::CallData);
+			{
+				if (!referenceType->interfaceType(false))
+					solAssert(m_errorReporter.hasErrors(), "");
+				else
+					result = referenceType->validForLocation(DataLocation::CallData);
+			}
 		}
 		if (!result)
 		{
diff --git a/libsolidity/ast/Types.h b/libsolidity/ast/Types.h
index 2ee749f1a..c043e19b3 100644
--- a/libsolidity/ast/Types.h
+++ b/libsolidity/ast/Types.h
@@ -769,6 +769,8 @@ public:
 	bool isPointer() const;
 
 	/// @returns true if this is valid to be stored in data location _loc
+	/// The function mostly checks sizes. For calldata, this should only be called
+	/// if the type has an interfaceType.
 	virtual BoolResult validForLocation(DataLocation _loc) const = 0;
 
 	bool operator==(ReferenceType const& _other) const
diff --git a/test/libsolidity/syntaxTests/abiEncoder/external_functions_taking_internal_types_struct_array_with_function_type.sol b/test/libsolidity/syntaxTests/abiEncoder/external_functions_taking_internal_types_struct_array_with_function_type.sol
new file mode 100644
index 000000000..ad46b4abe
--- /dev/null
+++ b/test/libsolidity/syntaxTests/abiEncoder/external_functions_taking_internal_types_struct_array_with_function_type.sol
@@ -0,0 +1,8 @@
+pragma abicoder v2;
+
+contract C {
+    struct S { function() internal a; }
+    function f(S[2] memory) public {}
+}
+// ----
+// TypeError 4103: (89-100): Internal type is not allowed for public or external functions.
diff --git a/test/libsolidity/syntaxTests/abiEncoder/external_functions_taking_internal_types_struct_with_array_of_function_types.sol b/test/libsolidity/syntaxTests/abiEncoder/external_functions_taking_internal_types_struct_with_array_of_function_types.sol
new file mode 100644
index 000000000..ca0610e69
--- /dev/null
+++ b/test/libsolidity/syntaxTests/abiEncoder/external_functions_taking_internal_types_struct_with_array_of_function_types.sol
@@ -0,0 +1,8 @@
+pragma abicoder v2;
+
+contract C {
+    struct S { function() internal[2] a; }
+    function f(S memory) public {}
+}
+// ----
+// TypeError 4103: (92-100): Internal type is not allowed for public or external functions.