diff --git a/test/api/hb-subset-test.h b/test/api/hb-subset-test.h
index 12d402d33..e86256747 100644
--- a/test/api/hb-subset-test.h
+++ b/test/api/hb-subset-test.h
@@ -86,6 +86,7 @@ hb_subset_test_open_font (const char *font_path)
     return face;
   }
   g_assert (false);
+  return NULL;
 }
 
 static inline hb_face_t *