diff --git a/changelog/fixed/timeless-tortoise.md b/changelog/fixed/timeless-tortoise.md
new file mode 100644
index 0000000000..e29259f3fc
--- /dev/null
+++ b/changelog/fixed/timeless-tortoise.md
@@ -0,0 +1 @@
+`ActivityHandle.describe()` now returns `None` as the `expiration_time` of a Standalone Activity that has no schedule-to-close timeout, instead of a naive `datetime.min`.
diff --git a/temporalio/client/_activity.py b/temporalio/client/_activity.py
index df7cd5c283..ec127d6313 100644
--- a/temporalio/client/_activity.py
+++ b/temporalio/client/_activity.py
@@ -362,7 +362,7 @@ def _from_resp(
             expiration_time=(
                 resp.info.expiration_time.ToDatetime(tzinfo=timezone.utc)
                 if resp.info.HasField("expiration_time")
-                else datetime.min
+                else None
             ),
             heartbeat_timeout=(
                 resp.info.heartbeat_timeout.ToTimedelta()
diff --git a/tests/test_activity.py b/tests/test_activity.py
index b3208d951d..d0a5de60a7 100644
--- a/tests/test_activity.py
+++ b/tests/test_activity.py
@@ -167,6 +167,23 @@ async def test_describe(self, client: Client, activity_handle: ActivityHandle):
         assert desc.next_attempt_schedule_time is None
         assert desc.retry_policy is not None
 
+    async def test_describe_without_schedule_to_close_timeout(
+        self, client: Client, env: WorkflowEnvironment, task_queue: str
+    ):
+        if env.supports_time_skipping_v1:
+            pytest.skip(
+                "Java test server: https://github.com/temporalio/sdk-java/issues/2741"
+            )
+        activity_handle = await client.start_activity(
+            heartbeat_fail_increment,
+            args=(1,),
+            id=str(uuid.uuid4()),
+            task_queue=task_queue,
+            start_to_close_timeout=timedelta(minutes=1),
+        )
+        desc = await activity_handle.describe()
+        assert desc.expiration_time is None  # no schedule-to-close timeout
+
     async def test_describe_payloads(
         self, client: Client, activity_handle: ActivityHandle, task_queue: str
     ):