diff --git a/lisp/help-fns.el b/lisp/help-fns.el
index 2c635ffa50..bcf33131fa 100644
--- a/lisp/help-fns.el
+++ b/lisp/help-fns.el
@@ -319,6 +319,7 @@ find-lisp-object-file-name
 	  (help-C-file-name type 'subr)
 	'C-source))
      ((and (not file-name) (symbolp object)
+           (eq type 'defvar)
 	   (integerp (get object 'variable-documentation)))
       ;; A variable defined in C.  The form is from `describe-variable'.
       (if (get-buffer " *DOC*")