diff --git a/libavcodec/mpegvideo_xvmc.c b/libavcodec/mpegvideo_xvmc.c
index 06c7bfc329..3d56bec374 100644
--- a/libavcodec/mpegvideo_xvmc.c
+++ b/libavcodec/mpegvideo_xvmc.c
@@ -61,7 +61,7 @@ void ff_xvmc_pack_pblocks(MpegEncContext *s, int cbp)
             s->pblocks[i] = (short *)(&s->block[j++]);
         else
             s->pblocks[i] = NULL;
-        cbp+=cbp;
+        cbp += cbp;
     }
 }