diff --git a/lisp/shell.el b/lisp/shell.el
index e6b315ee5c0..ca02d602966 100644
--- a/lisp/shell.el
+++ b/lisp/shell.el
@@ -720,9 +720,10 @@ shell-mode
   ;; edit this directory.  But it is useful in the buffer list and menus.
   (setq list-buffers-directory (expand-file-name default-directory))
   ;; shell-dependent assignments.
-  (when (ring-empty-p comint-input-ring)
+  (when (and (ring-empty-p comint-input-ring)
+             shell--start-prog)
     (let ((remote (file-remote-p default-directory))
-          (shell (or shell--start-prog ""))
+          (shell shell--start-prog)
           (hsize (getenv "HISTSIZE"))
           (hfile (getenv "HISTFILE")))
       (when remote