Index: Logbook-1.5.3/logbook/queues.py
===================================================================
--- Logbook-1.5.3.orig/logbook/queues.py
+++ Logbook-1.5.3/logbook/queues.py
@@ -229,7 +229,8 @@ class ZeroMQHandler(Handler):
             self.export_record(record)).encode("utf-8"))
 
     def close(self, linger=-1):
-        self.socket.close(linger)
+        if hasattr(self, 'socket'):
+            self.socket.close(linger)
 
     def __del__(self):
         # When the Handler is deleted we must close our socket in a