diff --git a/stdlib/3/datetime.pyi b/stdlib/3/datetime.pyi
index dd161a5f9..382a587b9 100644
--- a/stdlib/3/datetime.pyi
+++ b/stdlib/3/datetime.pyi
@@ -2,7 +2,7 @@
 
 # NOTE: These are incomplete!
 
-from typing import Optional, SupportsAbs, Tuple, Union, overload
+from typing import Optional, SupportsAbs, Tuple, overload
 
 MINYEAR = 0
 MAXYEAR = 0
@@ -97,7 +97,7 @@ class time:
     def tzname(self) -> Optional[str]: ...
     def dst(self) -> Optional[int]: ...
     def replace(self, hour: int = ..., minute: int = ..., second: int = ...,
-                microsecond: int = ..., tzinfo: Union[_tzinfo, bool] = ...) -> time: ...
+                microsecond: int = ..., tzinfo: _tzinfo = None) -> time: ...
 
 _date = date
 _time = time
@@ -197,7 +197,7 @@ class datetime:
     def timetz(self) -> _time: ...
     def replace(self, year: int = ..., month: int = ..., day: int = ..., hour: int = ...,
                 minute: int = ..., second: int = ..., microsecond: int = ..., tzinfo:
-                Union[_tzinfo, bool] = ...) -> datetime: ...
+                _tzinfo = None) -> datetime: ...
     def astimezone(self, tz: _tzinfo = ...) -> datetime: ...
     def ctime(self) -> str: ...
     def isoformat(self, sep: str = ...) -> str: ...