diff --git a/lisp/textmodes/ispell.el b/lisp/textmodes/ispell.el
index 7ae2c0cfa8a..1c9b3db2748 100644
--- a/lisp/textmodes/ispell.el
+++ b/lisp/textmodes/ispell.el
@@ -107,6 +107,7 @@
 ;;; Code:
 
 (eval-when-compile (require 'cl-lib))
+(require 'subr-x)
 
 (defvar mail-yank-prefix)