diff --git a/ngx_rtmp_amf.c b/ngx_rtmp_amf.c
index b904651..920d931 100644
--- a/ngx_rtmp_amf.c
+++ b/ngx_rtmp_amf.c
@@ -328,7 +328,7 @@ ngx_rtmp_amf_read(ngx_rtmp_amf_ctx_t *ctx, ngx_rtmp_amf_elt_t *elts,
         } else {
             switch (ngx_rtmp_amf_get(ctx, &type8, 1)) {
                 case NGX_DONE:
-                    if (elts->type & NGX_RTMP_AMF_OPTIONAL) {
+                    if (elts && elts->type & NGX_RTMP_AMF_OPTIONAL) {
                         return NGX_OK;
                     }
                     /* fall through */
diff --git a/ngx_rtmp_handler.c b/ngx_rtmp_handler.c
index a8bef61..1b13b19 100644
--- a/ngx_rtmp_handler.c
+++ b/ngx_rtmp_handler.c
@@ -241,7 +241,9 @@ ngx_rtmp_recv(ngx_event_t *rev)
                     "reusing formerly read data: %d", old_size);
 
             b->pos = b->start;
-            b->last = ngx_movemem(b->pos, old_pos, old_size);
+
+            size = ngx_min((size_t) (b->end - b->start), old_size);
+            b->last = ngx_movemem(b->pos, old_pos, size);
 
             if (s->in_chunk_size_changing) {
                 ngx_rtmp_finalize_set_chunk_size(s);