diff --git a/components/shared/message_broker_wrapper.py b/components/shared/message_broker_wrapper.py
index fbe5ae0..81824ef 100644
--- a/components/shared/message_broker_wrapper.py
+++ b/components/shared/message_broker_wrapper.py
@@ -38,7 +38,8 @@ class MBWrapper:
 
     def setup_receiver(self):
         assert self._type != 'sender', 'MBWrapper is already a sender. Use another MBWrapper.'
-        assert self.callback, 'Please setup MBWrapper with "on response" self.callback which can handle a byte string as input.'
+        assert self.callback, \
+            'Please setup MBWrapper with "on response" self.callback which can handle a byte string as input.'
 
         def consumer():
             self._setup_channel()