diff --git a/libavcodec/mpeg12.c b/libavcodec/mpeg12.c
index 79bf31dff0..f0aecd9803 100644
--- a/libavcodec/mpeg12.c
+++ b/libavcodec/mpeg12.c
@@ -1396,6 +1396,7 @@ static int mpeg1_decode_sequence(AVCodecContext *avctx,
         s->width = width;
         s->height = height;
         s->has_b_frames = 1;
+        s->avctx = avctx;
         avctx->width = width;
         avctx->height = height;
         avctx->frame_rate = frame_rate_tab[s->frame_rate_index];