diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index 8598c1f..8a79e29 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -1,3 +1,9 @@
+3.1.1
+-----
+
+* Since 3.8, CancelledError is a subclass of BaseException rather than Exception, so we need to catch it explicitly.
+* Enabled `mypy` for `wrapper` function.
+
 3.1.0
 -----
 
diff --git a/memoize/statuses.py b/memoize/statuses.py
index 06c0d68..9ae62b0 100644
--- a/memoize/statuses.py
+++ b/memoize/statuses.py
@@ -5,7 +5,7 @@
 import datetime
 import logging
 from abc import ABCMeta, abstractmethod
-from asyncio import Future
+from asyncio import Future, CancelledError
 from typing import Dict, Awaitable, Union
 
 from memoize.entry import CacheKey, CacheEntry
@@ -30,7 +30,7 @@ def mark_updated(self, key: CacheKey, entry: CacheEntry) -> None:
         raise NotImplementedError()
 
     @abstractmethod
-    def mark_update_aborted(self, key: CacheKey, exception: Exception) -> None:
+    def mark_update_aborted(self, key: CacheKey, exception: Union[Exception, CancelledError]) -> None:
         """Informs that update failed to complete.
         Calls to 'is_being_updated' will return False until 'mark_being_updated' will be called.
         Accepts exception to propagate it across all clients awaiting an update."""
@@ -79,7 +79,7 @@ def mark_updated(self, key: CacheKey, entry: CacheEntry) -> None:
         update = self._updates_in_progress.pop(key)
         update.set_result(entry)
 
-    def mark_update_aborted(self, key: CacheKey, exception: Exception) -> None:
+    def mark_update_aborted(self, key: CacheKey, exception: Union[Exception, CancelledError]) -> None:
         if key not in self._updates_in_progress:
             raise ValueError('Key {} is not being updated'.format(key))
         update = self._updates_in_progress.pop(key)
diff --git a/memoize/wrapper.py b/memoize/wrapper.py
index 9875072..d257917 100644
--- a/memoize/wrapper.py
+++ b/memoize/wrapper.py
@@ -6,7 +6,7 @@
 import datetime
 import functools
 import logging
-from asyncio import Future
+from asyncio import Future, CancelledError
 from typing import Optional, Callable
 
 from memoize.configuration import CacheConfiguration, NotConfiguredCacheCalledException, \
@@ -17,8 +17,8 @@
 from memoize.statuses import UpdateStatuses, InMemoryLocks
 
 
-def memoize(method: Optional[Callable] = None, configuration: CacheConfiguration = None,
-            invalidation: InvalidationSupport = None, update_statuses: UpdateStatuses = None):
+def memoize(method: Optional[Callable] = None, configuration: Optional[CacheConfiguration] = None,
+            invalidation: Optional[InvalidationSupport] = None, update_statuses: Optional[UpdateStatuses] = None):
     """Wraps function with memoization.
 
     If entry reaches time it should be updated, refresh is performed in background,
@@ -116,14 +116,14 @@ async def refresh(actual_entry: Optional[CacheEntry], key: CacheKey,
                 logger.debug('Timeout for %s: %s', key, e)
                 update_statuses.mark_update_aborted(key, e)
                 raise CachedMethodFailedException('Refresh timed out') from e
-            except Exception as e:
+            except (Exception, CancelledError) as e:
                 logger.debug('Error while refreshing cache for %s: %s', key, e)
                 update_statuses.mark_update_aborted(key, e)
                 raise CachedMethodFailedException('Refresh failed to complete') from e
 
     @functools.wraps(method)
     async def wrapper(*args, **kwargs):
-        if not configuration.configured():
+        if configuration is None or not configuration.configured():
             raise NotConfiguredCacheCalledException()
 
         configuration_snapshot = MutableCacheConfiguration.initialized_with(configuration)
diff --git a/mypy.ini b/mypy.ini
index d3d503f..9384ef3 100644
--- a/mypy.ini
+++ b/mypy.ini
@@ -1,2 +1,3 @@
 [mypy]
 no_implicit_optional=False
+check_untyped_defs=True
\ No newline at end of file
diff --git a/setup.py b/setup.py
index 74e4a2f..22ab504 100644
--- a/setup.py
+++ b/setup.py
@@ -11,7 +11,7 @@ def prepare_description():
 
 setup(
     name='py-memoize',
-    version='3.1.0',
+    version='3.1.1',
     author='Michal Zmuda',
     author_email='zmu.michal@gmail.com',
     url='https://github.com/DreamLab/memoize',
diff --git a/tests/end2end/test_wrapper.py b/tests/end2end/test_wrapper.py
index 2441ed9..6a40f7a 100644
--- a/tests/end2end/test_wrapper.py
+++ b/tests/end2end/test_wrapper.py
@@ -1,5 +1,6 @@
 import asyncio
 import time
+from asyncio import CancelledError
 from datetime import timedelta
 from unittest.mock import Mock
 
@@ -174,6 +175,37 @@ async def get_value(arg, kwarg=None):
         assert context.value.__class__ == CachedMethodFailedException
         assert str(context.value.__cause__) == str(ValueError('stub0'))
 
+    async def test_should_return_cancelled_exception_for_all_concurrent_callers(self):
+        # given
+        value = 0
+
+        @memoize()
+        async def get_value(arg, kwarg=None):
+            new_task = asyncio.create_task(asyncio.sleep(1))
+            new_task.cancel()  # this will raise CancelledError
+            await new_task
+
+        # when
+        res1 = get_value('test', kwarg='args1')
+        res2 = get_value('test', kwarg='args1')
+        res3 = get_value('test', kwarg='args1')
+
+        # then
+        with pytest.raises(Exception) as context:
+            await res1
+        assert context.value.__class__ == CachedMethodFailedException
+        assert str(context.value.__cause__) == str(CancelledError())
+
+        with pytest.raises(Exception) as context:
+            await res2
+        assert context.value.__class__ == CachedMethodFailedException
+        assert str(context.value.__cause__) == str(CancelledError())
+
+        with pytest.raises(Exception) as context:
+            await res3
+        assert context.value.__class__ == CachedMethodFailedException
+        assert str(context.value.__cause__) == str(CancelledError())
+
     async def test_should_return_timeout_for_all_concurrent_callers(self):
         # given
         value = 0