diff --git a/tox.ini b/tox.ini
index 5ac8358..471c6a7 100644
--- a/tox.ini
+++ b/tox.ini
@@ -4,6 +4,8 @@ envlist = py34, py27, pep8, docs
 skipsdist = True
 
 [testenv]
+setenv = LANGUAGE=en_US
+         LC_ALL=en_US.utf-8
 usedevelop = True
 install_command = pip install -U --force-reinstall {opts} {packages}
 deps = -r{toxinidir}/requirements.txt