diff --git a/tox.ini b/tox.ini
index 20ba6546..3619edf4 100644
--- a/tox.ini
+++ b/tox.ini
@@ -11,8 +11,10 @@ deps =
      nose
      pep8==1.5.7
      pyflakes
+
+# https://github.com/gabrielfalcao/HTTPretty/issues/223
 setenv =
-    LC_ALL = C
+    LC_ALL = en_US.utf-8
 
 [testenv:py26]
 commands = nosetests {posargs:tests}