diff --git a/lisp/emacs-lisp/eieio-custom.el b/lisp/emacs-lisp/eieio-custom.el
index 3f5291d0dee..375a1652d3d 100644
--- a/lisp/emacs-lisp/eieio-custom.el
+++ b/lisp/emacs-lisp/eieio-custom.el
@@ -31,6 +31,7 @@
 ;; `:custom'.
 
 (require 'eieio)
+(require 'eieio-base) ;; For `eieio-named's slot.
 (require 'widget)
 (require 'wid-edit)