diff --git a/libavformat/utils.c b/libavformat/utils.c
index 658da8f951..e51884774b 100644
--- a/libavformat/utils.c
+++ b/libavformat/utils.c
@@ -791,6 +791,7 @@ static int is_intra_only(AVCodecContext *enc){
         case CODEC_ID_VCR1:
         case CODEC_ID_DNXHD:
         case CODEC_ID_JPEG2000:
+        case CODEC_ID_MDEC:
             return 1;
         default: break;
         }