diff --git a/server/app.py b/server/app.py
index bf03759..3192b59 100644
--- a/server/app.py
+++ b/server/app.py
@@ -234,8 +234,8 @@ TIMEDELTA_FORMAT = (
 )
 
 
-@flask_app.template_filter()
-def timedelta(seconds: int) -> str:
+@flask_app.template_filter("timedelta")
+def _filter_timedelta(seconds: int) -> str:
     delta = timedelta(seconds=seconds)
     ret = ""
     for unit in TIMEDELTA_FORMAT: