diff --git a/stdlib/2/__builtin__.pyi b/stdlib/2/__builtin__.pyi
index e5fda2f31734..1fdb7c66b7df 100644
--- a/stdlib/2/__builtin__.pyi
+++ b/stdlib/2/__builtin__.pyi
@@ -1049,24 +1049,24 @@ class set(MutableSet[_T], Generic[_T]):
     def __gt__(self, s: AbstractSet[object]) -> bool: ...
     __hash__: None  # type: ignore
 
-class frozenset(AbstractSet[_T], Generic[_T]):
-    def __init__(self, iterable: Iterable[_T] = ...) -> None: ...
-    def copy(self) -> FrozenSet[_T]: ...
-    def difference(self, *s: Iterable[object]) -> FrozenSet[_T]: ...
-    def intersection(self, *s: Iterable[object]) -> FrozenSet[_T]: ...
-    def isdisjoint(self, s: Iterable[_T]) -> bool: ...
+class frozenset(AbstractSet[_T_co], Generic[_T_co]):
+    def __init__(self, iterable: Iterable[_T_co] = ...) -> None: ...
+    def copy(self) -> FrozenSet[_T_co]: ...
+    def difference(self, *s: Iterable[object]) -> FrozenSet[_T_co]: ...
+    def intersection(self, *s: Iterable[object]) -> FrozenSet[_T_co]: ...
+    def isdisjoint(self, s: Iterable[_T_co]) -> bool: ...
     def issubset(self, s: Iterable[object]) -> bool: ...
     def issuperset(self, s: Iterable[object]) -> bool: ...
-    def symmetric_difference(self, s: Iterable[_T]) -> FrozenSet[_T]: ...
-    def union(self, *s: Iterable[_T]) -> FrozenSet[_T]: ...
+    def symmetric_difference(self, s: Iterable[_T_co]) -> FrozenSet[_T_co]: ...
+    def union(self, *s: Iterable[_T_co]) -> FrozenSet[_T_co]: ...
     def __len__(self) -> int: ...
     def __contains__(self, o: object) -> bool: ...
-    def __iter__(self) -> Iterator[_T]: ...
+    def __iter__(self) -> Iterator[_T_co]: ...
     def __str__(self) -> str: ...
-    def __and__(self, s: AbstractSet[_T]) -> FrozenSet[_T]: ...
-    def __or__(self, s: AbstractSet[_S]) -> FrozenSet[Union[_T, _S]]: ...
-    def __sub__(self, s: AbstractSet[_T]) -> FrozenSet[_T]: ...
-    def __xor__(self, s: AbstractSet[_S]) -> FrozenSet[Union[_T, _S]]: ...
+    def __and__(self, s: AbstractSet[_T_co]) -> FrozenSet[_T_co]: ...
+    def __or__(self, s: AbstractSet[_S]) -> FrozenSet[Union[_T_co, _S]]: ...
+    def __sub__(self, s: AbstractSet[_T_co]) -> FrozenSet[_T_co]: ...
+    def __xor__(self, s: AbstractSet[_S]) -> FrozenSet[Union[_T_co, _S]]: ...
     def __le__(self, s: AbstractSet[object]) -> bool: ...
     def __lt__(self, s: AbstractSet[object]) -> bool: ...
     def __ge__(self, s: AbstractSet[object]) -> bool: ...
diff --git a/stdlib/2and3/builtins.pyi b/stdlib/2and3/builtins.pyi
index e5fda2f31734..1fdb7c66b7df 100644
--- a/stdlib/2and3/builtins.pyi
+++ b/stdlib/2and3/builtins.pyi
@@ -1049,24 +1049,24 @@ class set(MutableSet[_T], Generic[_T]):
     def __gt__(self, s: AbstractSet[object]) -> bool: ...
     __hash__: None  # type: ignore
 
-class frozenset(AbstractSet[_T], Generic[_T]):
-    def __init__(self, iterable: Iterable[_T] = ...) -> None: ...
-    def copy(self) -> FrozenSet[_T]: ...
-    def difference(self, *s: Iterable[object]) -> FrozenSet[_T]: ...
-    def intersection(self, *s: Iterable[object]) -> FrozenSet[_T]: ...
-    def isdisjoint(self, s: Iterable[_T]) -> bool: ...
+class frozenset(AbstractSet[_T_co], Generic[_T_co]):
+    def __init__(self, iterable: Iterable[_T_co] = ...) -> None: ...
+    def copy(self) -> FrozenSet[_T_co]: ...
+    def difference(self, *s: Iterable[object]) -> FrozenSet[_T_co]: ...
+    def intersection(self, *s: Iterable[object]) -> FrozenSet[_T_co]: ...
+    def isdisjoint(self, s: Iterable[_T_co]) -> bool: ...
     def issubset(self, s: Iterable[object]) -> bool: ...
     def issuperset(self, s: Iterable[object]) -> bool: ...
-    def symmetric_difference(self, s: Iterable[_T]) -> FrozenSet[_T]: ...
-    def union(self, *s: Iterable[_T]) -> FrozenSet[_T]: ...
+    def symmetric_difference(self, s: Iterable[_T_co]) -> FrozenSet[_T_co]: ...
+    def union(self, *s: Iterable[_T_co]) -> FrozenSet[_T_co]: ...
     def __len__(self) -> int: ...
     def __contains__(self, o: object) -> bool: ...
-    def __iter__(self) -> Iterator[_T]: ...
+    def __iter__(self) -> Iterator[_T_co]: ...
     def __str__(self) -> str: ...
-    def __and__(self, s: AbstractSet[_T]) -> FrozenSet[_T]: ...
-    def __or__(self, s: AbstractSet[_S]) -> FrozenSet[Union[_T, _S]]: ...
-    def __sub__(self, s: AbstractSet[_T]) -> FrozenSet[_T]: ...
-    def __xor__(self, s: AbstractSet[_S]) -> FrozenSet[Union[_T, _S]]: ...
+    def __and__(self, s: AbstractSet[_T_co]) -> FrozenSet[_T_co]: ...
+    def __or__(self, s: AbstractSet[_S]) -> FrozenSet[Union[_T_co, _S]]: ...
+    def __sub__(self, s: AbstractSet[_T_co]) -> FrozenSet[_T_co]: ...
+    def __xor__(self, s: AbstractSet[_S]) -> FrozenSet[Union[_T_co, _S]]: ...
     def __le__(self, s: AbstractSet[object]) -> bool: ...
     def __lt__(self, s: AbstractSet[object]) -> bool: ...
     def __ge__(self, s: AbstractSet[object]) -> bool: ...