diff --git a/lisp/net/tramp.el b/lisp/net/tramp.el
index b4242c0e6a7..f350f2a40d8 100644
--- a/lisp/net/tramp.el
+++ b/lisp/net/tramp.el
@@ -4102,7 +4102,11 @@ this file, if that variable is non-nil."
 	      (file-exists-p tramp-auto-save-directory))
     (make-directory tramp-auto-save-directory t))
 
-  (let ((system-type 'not-windows)
+  (let ((system-type
+	 (if (and (stringp tramp-auto-save-directory)
+		  (file-remote-p tramp-auto-save-directory))
+	     'not-windows
+	   system-type))
 	(auto-save-file-name-transforms
 	 (if (and (null tramp-auto-save-directory)
 		  (boundp 'auto-save-file-name-transforms))