diff --git a/etebase_fastapi/collection.py b/etebase_fastapi/collection.py
index 9e64072..77abe0f 100644
--- a/etebase_fastapi/collection.py
+++ b/etebase_fastapi/collection.py
@@ -86,7 +86,7 @@ class CollectionItemRevision(BaseModel):
     uid: str
     meta: bytes
     deleted: bool
-    chunks: t.List[t.List[t.Union[str, bytes]]]
+    chunks: t.List[t.Tuple[str, t.Optional[bytes]]]
 
 
 class Item(BaseModel):