--- a/testing/marionette/client/marionette_driver/transport.py
+++ b/testing/marionette/client/marionette_driver/transport.py
@@ -271,14 +271,20 @@ class TcpTransport(object):
         self.last_id = self.last_id + 1
         cmd = Command(self.last_id, name, params)
         self.send(cmd)
         return self.receive()
 
     def close(self):
         """Close the socket."""
         if self.sock:
-            self.sock.shutdown(socket.SHUT_RDWR)
+            try:
+                self.sock.shutdown(socket.SHUT_RDWR)
+            except IOError as exc:
+                # Errno 57 is "socket not connected", which we don't care about here.
+                if exc.errno != 57:
+                    raise
+
             self.sock.close()
             self.sock = None
 
     def __del__(self):
         self.close()