diff --git a/libavcodec/avpacket.c b/libavcodec/avpacket.c
index 90b8215928..fe8113ab76 100644
--- a/libavcodec/avpacket.c
+++ b/libavcodec/avpacket.c
@@ -571,6 +571,8 @@ FF_ENABLE_DEPRECATION_WARNINGS
     dst->flags                = src->flags;
     dst->stream_index         = src->stream_index;
 
+    dst->side_data            = NULL;
+    dst->side_data_elems      = 0;
     for (i = 0; i < src->side_data_elems; i++) {
          enum AVPacketSideDataType type = src->side_data[i].type;
          int size          = src->side_data[i].size;