diff --git a/api/advent22_api/core/dav/webdav.py b/api/advent22_api/core/dav/webdav.py
index acb5097..2e60a16 100644
--- a/api/advent22_api/core/dav/webdav.py
+++ b/api/advent22_api/core/dav/webdav.py
@@ -95,7 +95,8 @@ class WebDAV:
         cls._webdav_client.upload_to(buffer, path)
 
         # invalidate cache entry
-        cls._cache.pop(davkey("read_bytes")(path))
+        # explicit slice as there is no "cls" argument
+        del cls._cache[davkey("read_bytes", slice(0, None))(path)]
 
     @classmethod
     async def write_str(cls, path: str, content: str, encoding="utf-8") -> None: