diff --git a/tests/libtest-core.sh b/tests/libtest-core.sh
index d0b7d372..ce0e4bb1 100644
--- a/tests/libtest-core.sh
+++ b/tests/libtest-core.sh
@@ -40,6 +40,8 @@ if locale -a | grep C.UTF-8 >/dev/null; then
 else
     export LC_ALL=C
 fi
+# A GNU extension, used whenever LC_ALL is not C
+unset LANGUAGE
 
 # This should really be the default IMO
 export G_DEBUG=fatal-warnings