Fix dangling reference.

diff --git a/src/imail/imail-imap.scm b/src/imail/imail-imap.scm
index 9690df2e5cab6faf437b48328fd39def93ab0558..39ab4e5be86ddaba03f48894c4868de68eeac490 100644 (file)
--- a/src/imail/imail-imap.scm
+++ b/src/imail/imail-imap.scm
@@ -139,7 +139,7 @@ USA.
   (cond ((string-ci=? "inbox" mailbox) "inbox")
        ((and (string-prefix-ci? "inbox/" mailbox)
              (not (string-prefix? "inbox/" mailbox)))
-        (substring-downcase mailbox 0 5))
+        (string-downcase (string-slice mailbox 0 5)))
        (else mailbox)))
 
 (define (compatible-imap-urls? url1 url2)