diff --git a/src/calibre/gui2/ui.py b/src/calibre/gui2/ui.py
index 4cfbcc019a..b762bf7b11 100644
--- a/src/calibre/gui2/ui.py
+++ b/src/calibre/gui2/ui.py
@@ -71,7 +71,8 @@ class Listener(Thread):  # {{{
     def close(self):
         self._run = False
         try:
-            self.listener.close()
+            if self.listener is not None:
+                self.listener.close()
         except:
             import traceback
             traceback.print_exc()