diff --git a/py-polars/polars/lazyframe/frame.py b/py-polars/polars/lazyframe/frame.py
index 074d269b0d2c..2cd4772bda8b 100644
--- a/py-polars/polars/lazyframe/frame.py
+++ b/py-polars/polars/lazyframe/frame.py
@@ -2286,7 +2286,7 @@ def sink_ipc(
         simplify_expression: bool = True,
         slice_pushdown: bool = True,
         no_optimization: bool = False,
-    ) -> DataFrame:
+    ) -> None:
         """
         Evaluate the query in streaming mode and write to an IPC file.
 
@@ -2368,7 +2368,7 @@ def sink_csv(
         simplify_expression: bool = True,
         slice_pushdown: bool = True,
         no_optimization: bool = False,
-    ) -> DataFrame:
+    ) -> None:
         """
         Evaluate the query in streaming mode and write to a CSV file.
 
@@ -2504,7 +2504,7 @@ def sink_ndjson(
         simplify_expression: bool = True,
         slice_pushdown: bool = True,
         no_optimization: bool = False,
-    ) -> DataFrame:
+    ) -> None:
         """
         Evaluate the query in streaming mode and write to an NDJSON file.