diff --git a/libavcodec/bmp.c b/libavcodec/bmp.c
index 3034f9b8d36965913b8a3676ad0f3e8a6291525c..2a4d83393ef4b8fa92639c6ba2ae36ab19d9af5f 100644
--- a/libavcodec/bmp.c
+++ b/libavcodec/bmp.c
@@ -177,7 +177,8 @@ static int bmp_decode_frame(AVCodecContext *avctx,
     buf += hsize;
     dsize = buf_size - hsize;
 
-    n = avctx->width * (depth / 8);
+    /* Line size in file multiple of 4 */
+    n = (avctx->width * (depth / 8) + 3) & ~3;
 
     if(n * avctx->height > dsize){
         av_log(avctx, AV_LOG_ERROR, "not enough data (%d < %d)\n",