diff --git a/src/c3nav/mapdata/models/update.py b/src/c3nav/mapdata/models/update.py
index 8f91f75d..8ca2f2d1 100644
--- a/src/c3nav/mapdata/models/update.py
+++ b/src/c3nav/mapdata/models/update.py
@@ -201,7 +201,7 @@ class MapUpdate(models.Model):
             last_geometry_update = ([None] + [update for update in new_updates if update.geometries_changed])[-1]
 
             if last_geometry_update is not None:
-                geometry_update_cache_key = MapUpdate.build_cache_key(last_geometry_update.to_tuple)
+                geometry_update_cache_key = MapUpdate.build_cache_key(*last_geometry_update.to_tuple)
 
                 from c3nav.mapdata.utils.cache.changes import changed_geometries
                 changed_geometries.reset()