diff --git a/notion_client/api_endpoints.py b/notion_client/api_endpoints.py
index 8660dac..d51289a 100644
--- a/notion_client/api_endpoints.py
+++ b/notion_client/api_endpoints.py
@@ -23,7 +23,7 @@ def append(self, block_id: str, **kwargs: Any) -> SyncAsync[Any]:
         return self.parent.request(
             path=f"blocks/{block_id}/children",
             method="PATCH",
-            body=pick(kwargs, "children"),
+            body=pick(kwargs, "children", "after"),
             auth=kwargs.get("auth"),
         )