diff --git a/stubs/reportlab/reportlab/platypus/doctemplate.pyi b/stubs/reportlab/reportlab/platypus/doctemplate.pyi
index 57b083ff1f2f..c3ffee40eb39 100644
--- a/stubs/reportlab/reportlab/platypus/doctemplate.pyi
+++ b/stubs/reportlab/reportlab/platypus/doctemplate.pyi
@@ -249,7 +249,9 @@ class BaseDocTemplate:
     def handle_breakBefore(self, flowables: list[Flowable]) -> None: ...
     def handle_keepWithNext(self, flowables: list[Flowable]) -> None: ...
     def handle_flowable(self, flowables: list[Flowable]) -> None: ...
-    def build(self, flowables: list[Flowable], filename: str | None = None, canvasmaker: _CanvasMaker = ...) -> None: ...
+    def build(
+        self, flowables: list[Flowable], filename: str | IO[bytes] | None = None, canvasmaker: _CanvasMaker = ...
+    ) -> None: ...
     def notify(self, kind: str, stuff: Any) -> None: ...
     def pageRef(self, label: str) -> None: ...
     def multiBuild(self, story: list[Flowable], maxPasses: int = 10, **buildKwds: Any) -> int: ...