diff --git a/tests/atlocal.in b/tests/atlocal.in
index 47137bb..e9bb908 100644
--- a/tests/atlocal.in
+++ b/tests/atlocal.in
@@ -16,4 +16,12 @@ G_ENABLE_DIAGNOSTIC=1
 
 # For the Unicode tests - makes sure that UTF-8 characters
 # are accepted on command lines.
-LC_ALL=C.UTF-8
+case $host in
+*-*-darwin*)
+	LANG=C
+	LC_CTYPE=UTF-8
+	;;
+*)
+	LC_ALL=C.UTF-8
+	;;
+esac