diff --git a/tox.ini b/tox.ini
index 7da60f5b..0dbe2358 100644
--- a/tox.ini
+++ b/tox.ini
@@ -10,6 +10,8 @@ setenv =
    VIRTUAL_ENV={envdir}
    OS_TEST_PATH=./karbor/tests/unit
    PYTHONWARNINGS=default::DeprecationWarning
+   LANGUAGE=en_US
+   LC_ALL=en_US.utf-8
 deps = -r{toxinidir}/test-requirements.txt
 commands = python setup.py test --slowest --testr-args='{posargs}'