diff --git a/rudderstack/analytics/client.py b/rudderstack/analytics/client.py
index 3949e114..453d0458 100644
--- a/rudderstack/analytics/client.py
+++ b/rudderstack/analytics/client.py
@@ -276,7 +276,7 @@ def _enqueue(self, msg):
         # Check message size.
         msg_size = len(json.dumps(msg, cls=DatetimeSerializer).encode())
         if msg_size > MAX_MSG_SIZE:
-            raise RuntimeError('Message exceeds %skb limit. (%s)', str(int(MAX_MSG_SIZE / 1024)), str(msg))
+            raise RuntimeError(f'Message exceeds {str(int(MAX_MSG_SIZE / 1024))}kb limit. ({str(msg)})')
 
         # if send is False, return msg as if it was successfully queued
         if not self.send: