diff --git a/src/documents/tasks.py b/src/documents/tasks.py
index a83c2e6cd..0f7e7e52a 100644
--- a/src/documents/tasks.py
+++ b/src/documents/tasks.py
@@ -97,7 +97,7 @@ def train_classifier():
             logger.debug("Training data unchanged.")
 
     except Exception as e:
-        logger.warning("Classifier error: " + str(e))
+        logger.warning(f"Classifier error: {e}")
 
 
 @shared_task(bind=True)