diff --git a/src/c3nav/mapdata/utils/cache/local.py b/src/c3nav/mapdata/utils/cache/local.py
index 8d9b2385..32df7fb6 100644
--- a/src/c3nav/mapdata/utils/cache/local.py
+++ b/src/c3nav/mapdata/utils/cache/local.py
@@ -69,6 +69,8 @@ class LocalCacheProxy:
         self._check_mapupdate()
         cache.set(key, value, expire)
         if LocalCacheProxy.enabled:
+            if self._items.get(None) is None:
+                self._items.set(OrderedDict())
             self._items.get()[key] = value
         self._prune()