diff --git a/libavcodec/error_resilience.c b/libavcodec/error_resilience.c
index 1abae53f41..35d0c609e5 100644
--- a/libavcodec/error_resilience.c
+++ b/libavcodec/error_resilience.c
@@ -437,7 +437,7 @@ static void guess_mv(ERContext *s)
     }
 
     if ((!(s->avctx->error_concealment&FF_EC_GUESS_MVS)) ||
-        num_avail <= mb_width / 2) {
+        num_avail <= FFMAX(mb_width, mb_height) / 2) {
         for (mb_y = 0; mb_y < mb_height; mb_y++) {
             for (mb_x = 0; mb_x < s->mb_width; mb_x++) {
                 const int mb_xy = mb_x + mb_y * s->mb_stride;