diff --git a/packetserver/http/server.py b/packetserver/http/server.py
index 274a9c1..612cb87 100644
--- a/packetserver/http/server.py
+++ b/packetserver/http/server.py
@@ -19,7 +19,6 @@ templates = Jinja2Templates(directory=BASE_DIR / "templates")
 
 from datetime import datetime, timezone
 
-@templates.env.filters.register
 def timestamp_to_date(ts):
     if ts is None:
         return "Never"
@@ -29,6 +28,9 @@ def timestamp_to_date(ts):
     except (ValueError, TypeError):
         return "Invalid"
 
+# Register the filter correctly
+templates.env.filters["timestamp_to_date"] = timestamp_to_date
+
 # Static files
 app.mount("/static", StaticFiles(directory=BASE_DIR / "static"), name="static")