diff --git a/libavcodec/imgconvert.c b/libavcodec/imgconvert.c
index cfb21a4776..ca1aec6adb 100644
--- a/libavcodec/imgconvert.c
+++ b/libavcodec/imgconvert.c
@@ -364,6 +364,8 @@ static void conv411(uint8_t *dst, int dst_wrap,
     int w, c;
     uint8_t *s1, *s2, *d;
 
+    width>>=1;
+
     for(;height > 0; height--) {
         s1 = src;
         s2 = src + src_wrap;