(defun elmo-folder-confirm-appends (appends)
   (let ((len (length appends))
        in)
-    (if (and (> len elmo-folder-update-threshold)
+    (if (and elmo-folder-update-threshold
+            (> len elmo-folder-update-threshold)
             elmo-folder-update-confirm)
        (if (y-or-n-p (format "Too many messages(%d).  Continue? " len))
            appends
                                    (max (- len in) 0)))
                  (throw 'end in))))
          (nthcdr (max (- len in) 0) appends))
-      (if (and (> len elmo-folder-update-threshold)
+      (if (and elmo-folder-update-threshold
+              (> len elmo-folder-update-threshold)
               (not elmo-folder-update-confirm))
          (nthcdr (max (- len elmo-folder-update-threshold) 0) appends)
        appends))))