diff --git a/lib/nghttp2_hd.c b/lib/nghttp2_hd.c
index 7de72220..7406269c 100644
--- a/lib/nghttp2_hd.c
+++ b/lib/nghttp2_hd.c
@@ -1412,6 +1412,10 @@ ssize_t nghttp2_hd_inflate_hd(nghttp2_hd_inflater *inflater,
   uint8_t *last = in + inlen;
   int rfin = 0;
 
+  if(inflater->ctx.bad) {
+    return NGHTTP2_ERR_HEADER_COMP;
+  }
+
   DEBUGF(fprintf(stderr, "nghtp2_hd_infalte_hd start state=%d\n",
                  inflater->state));
   hd_inflate_keep_free(inflater);
@@ -1477,6 +1481,7 @@ ssize_t nghttp2_hd_inflate_hd(nghttp2_hd_inflater *inflater,
         }
       } else {
         inflater->index = inflater->left;
+        assert(inflater->index > 0);
         --inflater->index;
         inflater->ent_name = nghttp2_hd_table_get(&inflater->ctx,
                                                   inflater->index);