diff --git a/gtk/gtktestutils.c b/gtk/gtktestutils.c
index a105a7b27f..9fe37861a8 100644
--- a/gtk/gtktestutils.c
+++ b/gtk/gtktestutils.c
@@ -77,7 +77,7 @@ gtk_test_init (int    *argcp,
 {
   g_test_init (argcp, argvp, NULL);
   gtk_disable_setlocale();
-  setlocale (LC_ALL, "C");
+  setlocale (LC_ALL, "en_US.UTF-8");
   g_test_bug_base ("http://bugzilla.gnome.org/show_bug.cgi?id=%s");
 
   /* XSendEvent() doesn't work yet on XI2 events.