diff --git a/oslo_i18n/fixture.py b/oslo_i18n/fixture.py
index 5c5fddc..7a69aff 100644
--- a/oslo_i18n/fixture.py
+++ b/oslo_i18n/fixture.py
@@ -160,5 +160,5 @@ class PrefixLazyTranslation(fixtures.Fixture):
             lambda *x, **y: self.languages))
         self.useFixture(fixtures.MonkeyPatch('gettext.translation',
                                              _prefix_translations))
-        self.useFixture(fixtures.MonkeyPatch('locale.getdefaultlocale',
+        self.useFixture(fixtures.MonkeyPatch('locale.getlocale',
                                              lambda *x, **y: self.locale))