diff --git a/libavcodec/mpegvideo.c b/libavcodec/mpegvideo.c
index a0d0c8b62dd674719006d92a32a945d3700096a7..e28d9b309bfc748e922a92ba873ac4cc4d1cead6 100644
--- a/libavcodec/mpegvideo.c
+++ b/libavcodec/mpegvideo.c
@@ -3497,7 +3497,8 @@ static void encode_mb(MpegEncContext *s, int motion_x, int motion_y)
             }
         }
         ff_set_qscale(s, last_qp + s->dquant);
-    }
+    }else if(s->flags&CODEC_FLAG_QP_RD)
+        ff_set_qscale(s, s->qscale + s->dquant);
 
     wrap_y = s->linesize;
     wrap_c = s->uvlinesize;