diff --git a/agenda/trip.py b/agenda/trip.py
index 616e29e..4ce6eca 100644
--- a/agenda/trip.py
+++ b/agenda/trip.py
@@ -286,7 +286,7 @@ def read_geojson(data_dir: str, filename: str) -> str:
 
 def get_trip_routes(trip: Trip) -> list[StrDict]:
     """Get routes for given trip to show on map."""
-    routes = []
+    routes: list[StrDict] = []
     seen_geojson = set()
     for t in trip.travel:
         if t["type"] == "ferry":