diff --git a/zulint/custom_rules.py b/zulint/custom_rules.py
index d9b5af7..272d482 100644
--- a/zulint/custom_rules.py
+++ b/zulint/custom_rules.py
@@ -100,7 +100,7 @@ def check_file_for_pattern(
             ok = False
 
         if unmatched_exclude_lines:
-            print("Please remove exclusions for file {fn}: {unmatched_exclude_lines}")
+            print(f"Please remove exclusions for file {fn}: {unmatched_exclude_lines}")
 
         return ok