diff --git a/gptel-transient.el b/gptel-transient.el
index 3d8634e..b4bbef2 100644
--- a/gptel-transient.el
+++ b/gptel-transient.el
@@ -101,7 +101,9 @@ Or is it the other way around?"
   "Set a generic refactor/rewrite message for the buffer."
   (if (derived-mode-p 'prog-mode)
       (format "You are a %s programmer. Refactor the following code. Generate only code, no explanation."
-              (substring (symbol-name major-mode) nil -5))
+              (thread-last (symbol-name major-mode)
+                           (string-remove-suffix "-mode")
+                           (string-remove-suffix "-ts")))
     (format "You are a prose editor. Rewrite the following text to be more professional.")))
 
 (defvar gptel--crowdsourced-prompts-url