diff --git a/stdlib/datetime.pyi b/stdlib/datetime.pyi
index 37d6a06df..c54de6159 100644
--- a/stdlib/datetime.pyi
+++ b/stdlib/datetime.pyi
@@ -118,13 +118,13 @@ class time:
     resolution: ClassVar[timedelta]
     def __new__(
         cls,
-        hour: SupportsIndex = ...,
-        minute: SupportsIndex = ...,
-        second: SupportsIndex = ...,
-        microsecond: SupportsIndex = ...,
-        tzinfo: _TzInfo | None = ...,
+        hour: SupportsIndex = 0,
+        minute: SupportsIndex = 0,
+        second: SupportsIndex = 0,
+        microsecond: SupportsIndex = 0,
+        tzinfo: _TzInfo | None = None,
         *,
-        fold: int = ...,
+        fold: int = 0,
     ) -> Self: ...
     @property
     def hour(self) -> int: ...
@@ -144,7 +144,7 @@ class time:
     def __gt__(self, value: time, /) -> bool: ...
     def __eq__(self, value: object, /) -> bool: ...
     def __hash__(self) -> int: ...
-    def isoformat(self, timespec: str = ...) -> str: ...
+    def isoformat(self, timespec: str = "auto") -> str: ...
     @classmethod
     def fromisoformat(cls, time_string: str, /) -> Self: ...
 
@@ -197,13 +197,13 @@ class timedelta:
     resolution: ClassVar[timedelta]
     def __new__(
         cls,
-        days: float = ...,
-        seconds: float = ...,
-        microseconds: float = ...,
-        milliseconds: float = ...,
-        minutes: float = ...,
-        hours: float = ...,
-        weeks: float = ...,
+        days: float = 0,
+        seconds: float = 0,
+        microseconds: float = 0,
+        milliseconds: float = 0,
+        minutes: float = 0,
+        hours: float = 0,
+        weeks: float = 0,
     ) -> Self: ...
     @property
     def days(self) -> int: ...
@@ -247,13 +247,13 @@ class datetime(date):
         year: SupportsIndex,
         month: SupportsIndex,
         day: SupportsIndex,
-        hour: SupportsIndex = ...,
-        minute: SupportsIndex = ...,
-        second: SupportsIndex = ...,
-        microsecond: SupportsIndex = ...,
-        tzinfo: _TzInfo | None = ...,
+        hour: SupportsIndex = 0,
+        minute: SupportsIndex = 0,
+        second: SupportsIndex = 0,
+        microsecond: SupportsIndex = 0,
+        tzinfo: _TzInfo | None = None,
         *,
-        fold: int = ...,
+        fold: int = 0,
     ) -> Self: ...
     @property
     def hour(self) -> int: ...
@@ -272,10 +272,10 @@ class datetime(date):
     # meaning it is only *safe* to pass it as a keyword argument on 3.12+
     if sys.version_info >= (3, 12):
         @classmethod
-        def fromtimestamp(cls, timestamp: float, tz: _TzInfo | None = ...) -> Self: ...
+        def fromtimestamp(cls, timestamp: float, tz: _TzInfo | None = None) -> Self: ...
     else:
         @classmethod
-        def fromtimestamp(cls, timestamp: float, /, tz: _TzInfo | None = ...) -> Self: ...
+        def fromtimestamp(cls, timestamp: float, /, tz: _TzInfo | None = None) -> Self: ...
 
     @classmethod
     @deprecated("Use timezone-aware objects to represent datetimes in UTC; e.g. by calling .fromtimestamp(datetime.timezone.utc)")
@@ -321,8 +321,8 @@ class datetime(date):
         *,
         fold: int = ...,
     ) -> Self: ...
-    def astimezone(self, tz: _TzInfo | None = ...) -> Self: ...
-    def isoformat(self, sep: str = ..., timespec: str = ...) -> str: ...
+    def astimezone(self, tz: _TzInfo | None = None) -> Self: ...
+    def isoformat(self, sep: str = "T", timespec: str = "auto") -> str: ...
     @classmethod
     def strptime(cls, date_string: str, format: str, /) -> Self: ...
     def utcoffset(self) -> timedelta | None: ...