diff --git a/HISTORY.rst b/HISTORY.rst
index e40db50..6bf181a 100644
--- a/HISTORY.rst
+++ b/HISTORY.rst
@@ -16,12 +16,13 @@ v0.9.0
 * Bugfix: `login_oauth` works after `client_enable_hires` has been called - tehkillerbee_
 * Bugfix: Sessions created without a config no longer share one `Config` object - tehkillerbee_
 * `save_session_to_file` and `load_session_from_file` now persist `expiry_time` - tehkillerbee_
-* `Session.expiry_time` is now a timezone-aware UTC datetime, replacing the deprecated `datetime.utcnow()`. Naive datetimes passed to `load_oauth_session` are still supported - tehkillerbee_
+* `Session.expiry_time` is now a timezone-aware UTC datetime, replacing the deprecated `datetime.utcnow()`. Naive datetimes passed to `load_oauth_session` are treated as UTC - tehkillerbee_
 * Added `AbuseDetected`, raised when TIDAL answers with an anti-abuse HTTP 403 - tehkillerbee_
 * Added `Config(backoff=...)`, enabled by default: stop sending requests after a rate limit or abuse response and raise `TidalBackoffError` until it has passed. Pass `backoff=False` to disable - tehkillerbee_
 * Bugfix: Non-JSON error responses and `Retry-After` given as a date no longer break error handling - tehkillerbee_
 * Bugfix: Parsing tracks and albums no longer fails when TIDAL returns no or empty artist information - tehkillerbee_
 * Parsed `Track` flags (`pay_to_stream`, `premium_streaming_only`, `editable`, `upload`, `spotlighted`) are now `False` instead of `None` when TIDAL omits them, and `url` is an empty string - tehkillerbee_
+* Bugfix: `load_oauth_session` accepts `expiry_time` as an ISO 8601 string. Applications that store it as text (e.g. High Tide) would otherwise fail on every request, now that the expiry time is checked before each request - Petru101_
 
 v0.8.11
 --------
@@ -324,4 +325,5 @@ v0.6.2
 .. _nilathedragon: https://github.com/nilathedragon
 .. _semohr: https://github.com/semohr
 .. _rafrombrc: https://github.com/rafrombrc
+.. _Petru101: https://github.com/Petru101
 
diff --git a/tests/test_token_refresh.py b/tests/test_token_refresh.py
index 27f66e4..f847f44 100644
--- a/tests/test_token_refresh.py
+++ b/tests/test_token_refresh.py
@@ -215,6 +215,65 @@ def test_failed_proactive_refresh_does_not_fail_the_request():
     assert session.request.basic_request("GET", "tracks/1").ok
 
 
+def _load_oauth_session(expiry_time):
+    session = _refreshing_session(None)
+    session.request_session.request.return_value = fake_response(
+        200, {"sessionId": "sid", "countryCode": "US", "userId": 1}
+    )
+    with mock.patch.object(tidalapi.user.User, "factory"):
+        assert session.load_oauth_session(
+            "Bearer", "old-access", "old-refresh", expiry_time, is_pkce=True
+        )
+    return session
+
+
+def test_load_oauth_session_accepts_expiry_time_string():
+    # A naive string, as stored by applications using a previous tidalapi version
+    now = datetime.datetime.now(datetime.timezone.utc).replace(tzinfo=None)
+    expired = now - datetime.timedelta(days=1)
+
+    session = _load_oauth_session(str(expired))
+
+    # The expired token is refreshed up front, which sets a new expiry time
+    session.request_session.post.assert_called_once()
+    assert session.access_token == "new-access"
+    assert session.expiry_time > datetime.datetime.now(datetime.timezone.utc)
+
+
+def test_load_oauth_session_accepts_iso_format_expiry_time():
+    expiry_time = datetime.datetime(2030, 1, 2, 3, 4, 5)
+
+    session = _load_oauth_session(expiry_time.isoformat())
+
+    assert session.expiry_time == expiry_time.replace(tzinfo=datetime.timezone.utc)
+    session.request_session.post.assert_not_called()
+
+
+def test_load_oauth_session_accepts_timezone_aware_expiry_time_string():
+    expiry_time = datetime.datetime(2030, 1, 2, 3, 4, 5, tzinfo=datetime.timezone.utc)
+
+    session = _load_oauth_session(str(expiry_time))
+
+    assert session.expiry_time == expiry_time
+    session.request_session.post.assert_not_called()
+
+
+def test_load_oauth_session_treats_naive_datetime_as_utc():
+    expiry_time = datetime.datetime(2030, 1, 2, 3, 4, 5)
+
+    session = _load_oauth_session(expiry_time)
+
+    assert session.expiry_time == expiry_time.replace(tzinfo=datetime.timezone.utc)
+    session.request_session.post.assert_not_called()
+
+
+def test_load_oauth_session_ignores_invalid_expiry_time_string():
+    session = _load_oauth_session("None")
+
+    assert session.expiry_time is None
+    session.request_session.post.assert_not_called()
+
+
 def test_session_file_round_trips_expiry_time(tmp_path):
     session_file = tmp_path / "session.json"
     expiry_time = datetime.datetime(2030, 1, 2, 3, 4, 5)
diff --git a/tidalapi/session.py b/tidalapi/session.py
index 2843a3b..7e4486e 100644
--- a/tidalapi/session.py
+++ b/tidalapi/session.py
@@ -384,7 +384,7 @@ def load_oauth_session(
         token_type: str,
         access_token: str,
         refresh_token: str | None = None,
-        expiry_time: datetime.datetime | None = None,
+        expiry_time: datetime.datetime | str | None = None,
         is_pkce: bool | None = False,
     ) -> bool:
         """Login to TIDAL using details from a previous OAuth login, automatically
@@ -394,10 +394,24 @@ def load_oauth_session(
         :param access_token: The access token received from an oauth login or refresh
         :param refresh_token: (Optional) A refresh token that lets you get a new access
             token after it has expired
-        :param expiry_time: (Optional) The datetime the access token will expire
+        :param expiry_time: (Optional) The datetime the access token will expire. A
+            string in ISO 8601 format (e.g. ``str(datetime)``) is accepted too. Values
+            without a timezone are treated as UTC
         :param is_pkce: (Optional) Is session pkce?
         :return: True if we believe the login was successful, otherwise false.
         """
+        if isinstance(expiry_time, str):
+            # Applications often store the expiry time as text
+            try:
+                expiry_time = datetime.datetime.fromisoformat(expiry_time)
+            except ValueError:
+                log.info("Ignoring invalid expiry_time %r", expiry_time)
+                expiry_time = None
+
+        if expiry_time is not None and expiry_time.tzinfo is None:
+            # Treat naive datetimes (e.g. from legacy utcnow()) as UTC
+            expiry_time = expiry_time.replace(tzinfo=datetime.timezone.utc)
+
         self.token_type = token_type
         self.access_token = access_token
         self.refresh_token = refresh_token