diff --git a/stubs/WebOb/webob/headers.pyi b/stubs/WebOb/webob/headers.pyi
index 86734b3255d0..8e14bf642561 100644
--- a/stubs/WebOb/webob/headers.pyi
+++ b/stubs/WebOb/webob/headers.pyi
@@ -29,7 +29,7 @@ class EnvironHeaders(MutableMapping[str, str]):
     def __getitem__(self, hname: str) -> str: ...
     def __setitem__(self, hname: str, value: str) -> None: ...
     def __delitem__(self, hname: str) -> None: ...
-    def keys(self) -> filter[str]: ...  # type: ignore[override]
+    def keys(self) -> Iterator[str]: ...  # type: ignore[override]
     def __contains__(self, hname: object) -> bool: ...
     def __len__(self) -> int: ...
     def __iter__(self) -> Iterator[str]: ...