Fix missing return
diff --git a/src/hb-ft.cc b/src/hb-ft.cc
index aa73e7b..57ab034 100644
--- a/src/hb-ft.cc
+++ b/src/hb-ft.cc
@@ -425,4 +425,6 @@
   if (font->destroy == (hb_destroy_func_t) FT_Done_Face ||
       font->destroy == (hb_destroy_func_t) _do_nothing)
     return (FT_Face) font->user_data;
+
+  return NULL;
 }