Minor warning fix again

test/api/test-ot-face.c

diff --git a/test/api/test-ot-face.c b/test/api/test-ot-face.c
index 9ebcb4e..12ac666 100644
--- a/test/api/test-ot-face.c
+++ b/test/api/test-ot-face.c
@@ -111,7 +111,7 @@
 }
 
 static void
-test_ot_var_axis_on_zero_named_instance ()
+test_ot_var_axis_on_zero_named_instance (void)
 {
   hb_face_t *face = hb_test_open_font_file ("fonts/Zycon.ttf");
   g_assert (hb_ot_var_get_axis_count (face));