diff --git a/lm-c99/ig-c99.ysl2 b/lm-c99/ig-c99.ysl2
index 323a56c..6808ff5 100644
--- a/lm-c99/ig-c99.ysl2
+++ b/lm-c99/ig-c99.ysl2
@@ -17,19 +17,29 @@ tstylesheet {
     // * object
     def "func:ig_c99_typeclass" {
         param "idltype";
+        const "resolved_type", "func:idl_type_get_resolved_type($idltype)";
+        const "resolved_typekind", "func:idl_type_get_typekind_of_type($resolved_type)";
 
         choose {
             when "func:idl_type_is_defined($idltype)"
                 choose {
-                    when "func:idl_type_is_of_typekind_basetype($idltype)"
+                    when "$resolved_typekind = 'basetype'"
+                        choose {
+                            when "$resolved_type = 'string'"
+                                result > object
+                            when "$resolved_type = 'binary'"
+                                result > object
+                            otherwise
+                                result > primitive
+                        }
+                    when "$resolved_typekind = 'enum'"
                         result > primitive
-                    when "func:idl_type_is_of_typekind_deftype($idltype)"
-                        result > primitive
-                    when "func:idl_type_is_of_typekind_enum($idltype)"
-                        result > primitive
-                    when "func:idl_type_is_of_typekind_struct($idltype)"
-                        result > primitive
-
+                    when "$resolved_typekind = 'struct'"
+                        result > object
+                    when "$resolved_typekind = 'generic'"
+                        result > object
+                    otherwise
+                         error > ig_c99_typeclass - cant determine typeclass of: «$idltype»
                 }
             otherwise
                 error > ig_c99_typeclass - is not a type: «$idltype»