diff --git a/tests/spdylay_frame_test.c b/tests/spdylay_frame_test.c
index 22c1f206..6c3edc22 100644
--- a/tests/spdylay_frame_test.c
+++ b/tests/spdylay_frame_test.c
@@ -44,6 +44,7 @@ static int get_packed_hd_len(uint8_t *data, size_t len_size)
   } else {
     /* Not supported */
     assert(0);
+    return 0;
   }
 }