diff --git a/libavformat/matroskadec.c b/libavformat/matroskadec.c
index 6cccbcbe03..49950956b6 100644
--- a/libavformat/matroskadec.c
+++ b/libavformat/matroskadec.c
@@ -3719,19 +3719,21 @@ static int matroska_parse_block_additional(MatroskaDemuxContext *matroska,
             av_free(hdrplus);
             return res;
         }
-        break;
+
+        return 0;
     }
     default:
-        side_data = av_packet_new_side_data(pkt, AV_PKT_DATA_MATROSKA_BLOCKADDITIONAL,
-                                            size + (size_t)8);
-        if (!side_data)
-            return AVERROR(ENOMEM);
-
-        AV_WB64(side_data, id);
-        memcpy(side_data + 8, data, size);
         break;
     }
 
+    side_data = av_packet_new_side_data(pkt, AV_PKT_DATA_MATROSKA_BLOCKADDITIONAL,
+                                        size + (size_t)8);
+    if (!side_data)
+        return AVERROR(ENOMEM);
+
+    AV_WB64(side_data, id);
+    memcpy(side_data + 8, data, size);
+
     return 0;
 }