diff --git a/editors/protobuf-mode.el b/editors/protobuf-mode.el
index f615a0afbc..1cef413757 100644
--- a/editors/protobuf-mode.el
+++ b/editors/protobuf-mode.el
@@ -64,12 +64,13 @@
 ;;; Code:
 
 (require 'cc-mode)
+(require 'cl)
 
 (eval-when-compile
   (require 'cc-langs)
   (require 'cc-fonts))
 
-;; This mode does not inherit properties from other modes. So, we do not use 
+;; This mode does not inherit properties from other modes. So, we do not use
 ;; the usual `c-add-language' function.
 (eval-and-compile
   (put 'protobuf-mode 'c-mode-prefix "protobuf-"))