diff --git a/lisp/emacs-lisp/cl-preloaded.el b/lisp/emacs-lisp/cl-preloaded.el
index 9445093f143..5235be52996 100644
--- a/lisp/emacs-lisp/cl-preloaded.el
+++ b/lisp/emacs-lisp/cl-preloaded.el
@@ -176,6 +176,7 @@ supertypes from the most specific to least specific.")
                        (i 0)
                        (offset (if type 0 1)))
                    (dolist (slot slots)
+                     (put (car slot) 'slot-name t)
                      (let* ((props (cl--plist-to-alist (cddr slot)))
                             (typep (assq :type props))
                             (type (if (null typep) t