diff --git a/test/api/test-subset-glyf.c b/test/api/test-subset-glyf.c
index 538960c54..98e12339a 100644
--- a/test/api/test-subset-glyf.c
+++ b/test/api/test-subset-glyf.c
@@ -73,6 +73,8 @@ test_subset_glyf_noop (void)
   hb_face_destroy (face_abc);
 }
 
+// TODO(grieger): test for long loca generation.
+
 int
 main (int argc, char **argv)
 {