diff --git a/src/django_watchfiles/__init__.py b/src/django_watchfiles/__init__.py
index f33ce54..9fe92d0 100644
--- a/src/django_watchfiles/__init__.py
+++ b/src/django_watchfiles/__init__.py
@@ -31,7 +31,7 @@ def watch_safely(f: Callable[[], Iterable[T]], default: T) -> Iterable[T]:
     Yield from `f()`, but when it fails, yield `default` once, log the exception and retry,
     unless there are 2 exceptions within 1 second, in which case the exception is raised.
     """
-    ts: Optional[float] = None
+    ts: float | None = None
     while True:
         try:
             yield from f()
@@ -68,8 +68,8 @@ def set_roots(self, roots: set[Path]) -> None:
     def stop(self) -> None:
         self.stop_event.set()
 
-    def __iter__(self) -> Generator[Set[FileChange], None, None]:
-        no_changes: Set[FileChange] = set()
+    def __iter__(self) -> Generator[set[FileChange], None, None]:
+        no_changes: set[FileChange] = set()
         while True:
             self.change_event.clear()
             for changes in watch_safely(