1 files changed, 2 insertions, 1 deletions

diff --git a/lisp/mouse.el b/lisp/mouse.el
index 7f9d080478a..b73967b99dc 100644
--- a/lisp/mouse.el
+++ b/lisp/mouse.el
@@ -625,7 +625,8 @@ This should be bound to a mouse drag event."
 
 (defun mouse-set-region-1 ()
   ;; Set transient-mark-mode for a little while.
-  (setq transient-mark-mode (or transient-mark-mode 'only))
+  (if (memq transient-mark-mode '(nil identity))
+      (setq transient-mark-mode 'only))
   (setq mouse-last-region-beg (region-beginning))
   (setq mouse-last-region-end (region-end))
   (setq mouse-last-region-tick (buffer-modified-tick)))