diff --git a/idl/idl_api.ysl2 b/idl/idl_api.ysl2
index fbc4da8..cf374c8 100644
--- a/idl/idl_api.ysl2
+++ b/idl/idl_api.ysl2
@@ -107,7 +107,7 @@ def "func:idl_type_get_type_of_deftype" {
         when "func:idl_type_is_of_typekind_deftype($idltype)"
             choose {
                 when "func:idl_typekind_is_generic($type_or_typekind)"
-                    result call "type_of_generic_deftype" with "deftype", "$deftype";
+                    result call "idl_type_of_generic_deftype" with "deftype", "$deftype";
                 otherwise
                     result "$type_or_typekind";
             }
@@ -116,7 +116,7 @@ def "func:idl_type_get_type_of_deftype" {
     }
 }
 
-function "type_of_generic_deftype" {
+function "idl_type_of_generic_deftype" {
     param "deftype";
     const "generic_type", "$deftype/as/@type";