diff --git a/libavcodec/xan.c b/libavcodec/xan.c
index 4c01c0013f..8b4ec82405 100644
--- a/libavcodec/xan.c
+++ b/libavcodec/xan.c
@@ -263,7 +263,7 @@ static inline void xan_wc3_copy_pixel_run(XanContext *s, AVFrame *frame,
     prevframe_index = (y + motion_y) * stride + x + motion_x;
     prevframe_x = x + motion_x;
 
-    if (prev_palette_plane == palette_plane && FFABS(curframe_index - prevframe_index) < pixel_count) {
+    if (prev_palette_plane == palette_plane && FFABS(motion_x + width*motion_y) < pixel_count) {
          avpriv_request_sample(s->avctx, "Overlapping copy");
          return ;
     }