diff --git a/libavcodec/vc1.c b/libavcodec/vc1.c
index ac2a4de98e..7cbf851f0d 100644
--- a/libavcodec/vc1.c
+++ b/libavcodec/vc1.c
@@ -814,6 +814,9 @@ static int decode_sequence_header(AVCodecContext *avctx, GetBitContext *gb)
     if (!v->res_fasttx)
     {
         v->s.dsp.vc1_inv_trans_8x8 = simple_idct;
+        v->s.dsp.vc1_inv_trans_8x4 = simple_idct84_add;
+        v->s.dsp.vc1_inv_trans_4x8 = simple_idct48_add;
+//        v->s.dsp.vc1_inv_trans_4x4 = simple_idct44_add;
     }
 
     v->fastuvmc =  get_bits1(gb); //common