diff --git a/lisp/subr.el b/lisp/subr.el
index 573f238f743..07909b894f5 100644
--- a/lisp/subr.el
+++ b/lisp/subr.el
@@ -4507,8 +4507,10 @@ to deactivate this transient map, regardless of KEEP-PRED."
                         ;; exit C-u.
                         t)
                        ((eq t keep-pred)
-                        (eq this-command
-                            (lookup-key map (this-command-keys-vector))))
+                        (let ((mc (lookup-key map (this-command-keys-vector))))
+                          ;; If the key is unbound `this-command` is
+                          ;; nil and so is `mc`.
+                          (and mc (eq this-command mc))))
                        (t (funcall keep-pred)))
                 (funcall exitfun)))))
     (add-hook 'pre-command-hook clearfun)