diff --git a/lib/nghttp2_hd.c b/lib/nghttp2_hd.c
index f331f057..1a64b8b9 100644
--- a/lib/nghttp2_hd.c
+++ b/lib/nghttp2_hd.c
@@ -1709,7 +1709,7 @@ ssize_t nghttp2_hd_inflate_hd(nghttp2_hd_inflater *inflater,
           inflater->state = NGHTTP2_HD_STATE_READ_INDEX;
         }
         inflater->index_required = (*in & 0x40) != 0;
-        inflater->no_index = (*in & 0x10u) != 0;
+        inflater->no_index = (*in & 0xf0u) ==  0x10u;
         DEBUGF(fprintf(stderr,
                        "inflatehd: indexing required=%d, no_index=%d\n",
                        inflater->index_required,