diff --git a/stubs/openpyxl/openpyxl/workbook/child.pyi b/stubs/openpyxl/openpyxl/workbook/child.pyi
index b347be49e..b74da8ee3 100644
--- a/stubs/openpyxl/openpyxl/workbook/child.pyi
+++ b/stubs/openpyxl/openpyxl/workbook/child.pyi
@@ -12,9 +12,9 @@ class _WorkbookChild:
     @property
     def encoding(self): ...
     @property
-    def title(self): ...
+    def title(self) -> str: ...
     @title.setter
-    def title(self, value) -> None: ...
+    def title(self, value: str | bytes) -> None: ...
     @property
     def oddHeader(self): ...
     @oddHeader.setter