diff --git a/tests/test_core.py b/tests/test_core.py

index dd69a96..c666a3a 100644

--- a/tests/test_core.py

+++ b/tests/test_core.py

@@ -389,13 +389,23 @@ def test_unknown_preferredencoding_warned_and_fallback():

     """Ensure a locale without a codec emits a warning."""

     @as_subprocess

     def child():

+        warnings.filterwarnings("error", category=UserWarning)

+        match = ('LookupError: unknown encoding: ---unknown--encoding---, '

+                 'defaulting to UTF-8 for keyboard.')

         with mock.patch('locale.getpreferredencoding') as get_enc:

             get_enc.return_value = '---unknown--encoding---'

-            with pytest.warns(UserWarning, match=(

-                    'LookupError: unknown encoding: ---unknown--encoding---, '

-                    'defaulting to UTF-8 for keyboard.')):

-                t = TestTerminal()

-                assert t._encoding == 'UTF-8'

+            try:

+                TestTerminal()

+            except UserWarning as e:

+                assert match in str(e)

+            else:

+                raise AssertionError('Did not raise warning')

+

+            warnings.filterwarnings("ignore", category=UserWarning)

+            t = TestTerminal()

+            assert t._encoding == 'UTF-8'

+

+        warnings.resetwarnings()

     child()