diff --git a/libavcodec/xxan.c b/libavcodec/xxan.c
index de1ea7f0e4..2c33f07a71 100644
--- a/libavcodec/xxan.c
+++ b/libavcodec/xxan.c
@@ -289,7 +289,8 @@ static int xan_decode_frame_type0(AVCodecContext *avctx)
             ybuf[j+1] = cur << 1;
             last = cur;
         }
-        ybuf[j] = last << 1;
+        if(j < avctx->width)
+            ybuf[j] = last << 1;
         prev_buf = ybuf;
         ybuf += avctx->width;
     }