diff --git a/rosbridge_library/src/rosbridge_library/internal/publishers.py b/rosbridge_library/src/rosbridge_library/internal/publishers.py
index 9b4215527..06198b4d9 100644
--- a/rosbridge_library/src/rosbridge_library/internal/publishers.py
+++ b/rosbridge_library/src/rosbridge_library/internal/publishers.py
@@ -281,12 +281,12 @@ def register(self, client_id, topic, msg_type=None, latch=False, queue_size=100)
              queue_size=queue_size)
         elif latch and self._publishers[topic].latched_client_id != client_id:
             logwarn("Client ID %s attempted to register topic [%s] as latched " +
-                    "but this topic was previously registered." % (client_id, topic))
+                    "but this topic was previously registered.", client_id, topic)
             logwarn("Only a single registered latched publisher is supported at the time")
         elif not latch and self._publishers[topic].latched_client_id:
             logwarn("New non-latched publisher registration for topic [%s] which is " +
                     "already registered as latched. but this topic was previously " +
-                    "registered." % topic)
+                    "registered.", topic)
             logwarn("Only a single registered latched publisher is supported at the time")
 
         if msg_type is not None: