1 files changed, 3 insertions, 3 deletions

diff --git a/lisp/mail/rmail.el b/lisp/mail/rmail.el
index d2329452ce4..6e3056da407 100644
--- a/lisp/mail/rmail.el
+++ b/lisp/mail/rmail.el
@@ -1803,9 +1803,9 @@ is non-nil if the user has supplied the password interactively.
                     ;; in case of multiple inboxes that need moving.
                     (concat ".newmail-"
                             (file-name-nondirectory
-                             (if (memq system-type '(windows-nt cygwin))
-                                 ;; cannot have "po:" in file name
-                                 (substring file 3)
+                             (if (memq system-type '(windows-nt cygwin ms-dos))
+                                 ;; cannot have colons in file name
+                                 (replace-regexp-in-string ":" "-" file)
                                file)))
                     ;; Use the directory of this rmail file
                     ;; because it's a nuisance to use the homedir