diff --git a/hummingbot/connector/exchange/kraken/kraken_order_book_tracker.py b/hummingbot/connector/exchange/kraken/kraken_order_book_tracker.py
index 8ac727f7d5..cce7530271 100644
--- a/hummingbot/connector/exchange/kraken/kraken_order_book_tracker.py
+++ b/hummingbot/connector/exchange/kraken/kraken_order_book_tracker.py
@@ -78,9 +78,7 @@ async def _order_book_diff_router(self):
                 # Log some statistics.
                 now: float = time.time()
                 if int(now / 60.0) > int(last_message_timestamp / 60.0):
-                    self.logger().debug("Diff messages processed: %d, rejected: %d",
-                                        messages_accepted,
-                                        messages_rejected)
+                    self.logger().debug(f"Diff messages processed: {messages_accepted}, rejected: {messages_rejected}")
                     messages_accepted = 0
                     messages_rejected = 0