diff --git a/src/clos/std-slot-value.lsp b/src/clos/std-slot-value.lsp
index 147655731..b661df3be 100644
--- a/src/clos/std-slot-value.lsp
+++ b/src/clos/std-slot-value.lsp
@@ -104,9 +104,10 @@
     `(let* ((i ,instance)
 	    (s (si::instance-sig i)))
        (declare (:read-only i s))
-       (when (si:sl-boundp s)
-	 (unless (eq s (class-slots (si::instance-class i)))
-	   (update-instance i))))))
+       (with-early-accessors (+standard-class-slots+)
+	 (when (si:sl-boundp s)
+	   (unless (eq s (class-slots (si::instance-class i)))
+	     (update-instance i)))))))
 
 ;;;
 ;;; STANDARD-CLASS INTERFACE