diff --git a/src/analyze.cpp b/src/analyze.cpp
index 638a31ab5..89e64ec54 100644
--- a/src/analyze.cpp
+++ b/src/analyze.cpp
@@ -1957,7 +1957,7 @@ static ZigType *analyze_fn_type(CodeGen *g, AstNode *proto_node, Scope *child_sc
 
     if(!is_valid_return_type(specified_return_type)){
         ErrorMsg* msg = add_node_error(g, fn_proto->return_type,
-            buf_sprintf("return type '%s' not allowed", buf_ptr(&specified_return_type->name)));
+            buf_sprintf("%s return type '%s' not allowed", type_id_name(specified_return_type->id), buf_ptr(&specified_return_type->name)));
         Tld *tld = find_decl(g, &fn_entry->fndef_scope->base, &specified_return_type->name);
         if (tld != nullptr) {
             add_error_note(g, msg, tld->source_node, buf_sprintf("type declared here"));
diff --git a/src/ir.cpp b/src/ir.cpp
index 67eabf504..d4db5455f 100644
--- a/src/ir.cpp
+++ b/src/ir.cpp
@@ -19342,7 +19342,7 @@ static IrInstGen *ir_analyze_fn_call(IrAnalyze *ira, IrInst* source_instr,
 
             if(!is_valid_return_type(specified_return_type)){
                 ErrorMsg *msg = ir_add_error(ira, source_instr,
-                    buf_sprintf("call to generic function with return type '%s' not allowed", buf_ptr(&specified_return_type->name)));
+                    buf_sprintf("call to generic function with %s return type '%s' not allowed", type_id_name(specified_return_type->id), buf_ptr(&specified_return_type->name)));
                 add_error_note(ira->codegen, msg, fn_proto_node, buf_sprintf("function declared here"));
 
                 Tld *tld = find_decl(ira->codegen, &fn_entry->fndef_scope->base, &specified_return_type->name);
diff --git a/test/compile_errors.zig b/test/compile_errors.zig
index 006bd3ef7..63a8a48be 100644
--- a/test/compile_errors.zig
+++ b/test/compile_errors.zig
@@ -6538,9 +6538,17 @@ pub fn addCases(cases: *tests.CompileErrorContext) void {
         \\export fn bar() !FooType {
         \\    return error.InvalidValue;
         \\}
+        \\export fn bav() !@TypeOf(null) {
+        \\    return error.InvalidValue;
+        \\}
+        \\export fn baz() !@TypeOf(undefined) {
+        \\    return error.InvalidValue;
+        \\}
     , &[_][]const u8{
-        "tmp.zig:2:18: error: return type 'FooType' not allowed",
+        "tmp.zig:2:18: error: Opaque return type 'FooType' not allowed",
         "tmp.zig:1:1: note: type declared here",
+        "tmp.zig:5:18: error: Null return type '(null)' not allowed",
+        "tmp.zig:8:18: error: Undefined return type '(undefined)' not allowed",
     });
 
     cases.add("generic function returning opaque type",
@@ -6551,10 +6559,20 @@ pub fn addCases(cases: *tests.CompileErrorContext) void {
         \\export fn bar() void {
         \\    _ = generic(FooType);
         \\}
+        \\export fn bav() void {
+        \\    _ = generic(@TypeOf(null));
+        \\}
+        \\export fn baz() void {
+        \\    _ = generic(@TypeOf(undefined));
+        \\}
     , &[_][]const u8{
-        "tmp.zig:6:16: error: call to generic function with return type 'FooType' not allowed",
+        "tmp.zig:6:16: error: call to generic function with Opaque return type 'FooType' not allowed",
         "tmp.zig:2:1: note: function declared here",
         "tmp.zig:1:1: note: type declared here",
+        "tmp.zig:9:16: error: call to generic function with Null return type '(null)' not allowed",
+        "tmp.zig:2:1: note: function declared here",
+        "tmp.zig:12:16: error: call to generic function with Undefined return type '(undefined)' not allowed",
+        "tmp.zig:2:1: note: function declared here",
     });
 
     cases.add( // fixed bug #2032