diff --git a/lisp/progmodes/cc-defs.el b/lisp/progmodes/cc-defs.el
index e45ab76ec07..2c793c8a99d 100644
--- a/lisp/progmodes/cc-defs.el
+++ b/lisp/progmodes/cc-defs.el
@@ -2579,7 +2579,8 @@ constant.  A file is identified by its base name."
 	;; dependencies on the `c-lang-const's in VAL.)
 	(setq val (c--macroexpand-all val))
 
-	(setq bindings `(cons (cons ',assigned-mode (lambda () ,val)) ,bindings)
+	(setq bindings `(cons (cons ',assigned-mode (lambda () nil ,val))
+			      ,bindings)
 	      args (cdr args))))
 
     ;; Compile in the other files that have provided source