diff --git a/apscheduler/util.py b/apscheduler/util.py
index 6f70f921..d929a482 100644
--- a/apscheduler/util.py
+++ b/apscheduler/util.py
@@ -90,8 +90,6 @@ def astimezone(obj):
     if isinstance(obj, six.string_types):
         return timezone(obj)
     if isinstance(obj, tzinfo):
-        if not hasattr(obj, 'localize') or not hasattr(obj, 'normalize'):
-            raise TypeError('Only timezones from the pytz library are supported')
         if obj.tzname(None) == 'local':
             raise ValueError(
                 'Unable to determine the name of the local timezone -- you must explicitly '
diff --git a/docs/migration.rst b/docs/migration.rst
index 72c07fdb..8dc17480 100644
--- a/docs/migration.rst
+++ b/docs/migration.rst
@@ -68,6 +68,7 @@ but if you were instantiating triggers manually before, then one must be supplie
 The only other backwards incompatible change was that ``get_next_fire_time()`` takes two arguments
 now: the previous fire time and the current datetime.
 
+.. note:: APScheduler 3.9.0 added experimental support for non-pytz timezones.
 
 From v1.x to 2.0
 ================
diff --git a/docs/versionhistory.rst b/docs/versionhistory.rst
index 2dffb247..55490fcb 100644
--- a/docs/versionhistory.rst
+++ b/docs/versionhistory.rst
@@ -4,6 +4,12 @@ Version history
 To find out how to migrate your application from a previous version of
 APScheduler, see the :doc:`migration section <migration>`.
 
+3.9.1
+-----
+
+* Removed a leftover check for pytz ``localize()`` and ``normalize()`` methods
+
+
 3.9.0
 -----
 
diff --git a/tests/test_util.py b/tests/test_util.py
index f7f900b3..64ad2330 100644
--- a/tests/test_util.py
+++ b/tests/test_util.py
@@ -94,8 +94,8 @@ def test_none(self):
         assert astimezone(None) is None
 
     def test_bad_timezone_type(self):
-        exc = pytest.raises(TypeError, astimezone, tzinfo())
-        assert 'Only timezones from the pytz library are supported' in str(exc.value)
+        pytest.raises(NotImplementedError, astimezone, tzinfo()).\
+            match(r'(a )?tzinfo subclass must (implement|override) tzname\(\)')
 
     def test_bad_local_timezone(self):
         zone = Mock(tzinfo, localize=None, normalize=None, tzname=lambda dt: 'local')