diff --git a/trio/_core/_multierror.py b/trio/_core/_multierror.py
index 6e4cb8b923..d55e89554d 100644
--- a/trio/_core/_multierror.py
+++ b/trio/_core/_multierror.py
@@ -261,7 +261,7 @@ def __str__(self) -> str:
     def __repr__(self) -> str:
         return f"<MultiError: {self}>"
 
-    @overload
+    @overload  # type: ignore[override]  # 'Exception' != '_ExceptionT'
     def derive(self, excs: Sequence[Exception], /) -> NonBaseMultiError:
         ...