diff --git a/lisp/ph.el b/lisp/ph.el
index 40abafaa802..f7cd052f3b4 100644
--- a/lisp/ph.el
+++ b/lisp/ph.el
@@ -63,6 +63,8 @@
 
 ;;; Code:
 
+(eval-when-compile (require 'cl))
+
 (require 'wid-edit)
 
 (if (not (fboundp 'make-overlay))