diff --git a/lisp/emacs-lisp/eieio-core.el b/lisp/emacs-lisp/eieio-core.el
index b6acab2a25a37779ecce34b1c4fa561a5a86c2c4..620b47e68d2ffac3a1324ab2f16cbdc46d00e43d 100644
--- a/lisp/emacs-lisp/eieio-core.el
+++ b/lisp/emacs-lisp/eieio-core.el
@@ -1085,9 +1085,10 @@ method invocation orders of the involved classes."
 These match if the argument is the name of a subclass of CLASS."
   (list eieio--generic-subclass-generalizer))
 
-(defun eieio-declare-slots (&rest slots)
+(defmacro eieio-declare-slots (&rest slots)
   "Declare that SLOTS are known eieio object slot names."
-  (setq eieio--known-slot-names (append slots eieio--known-slot-names)))
+  `(eval-when-compile
+     (setq eieio--known-slot-names (append ',slots eieio--known-slot-names))))
 
 (provide 'eieio-core)