diff --git a/libavformat/mov.c b/libavformat/mov.c
index 7455e3b5e5..39f30e432c 100644
--- a/libavformat/mov.c
+++ b/libavformat/mov.c
@@ -2486,9 +2486,9 @@ static int mov_open_dref(AVIOContext **pb, const char *src, MOVDref *ref,
             filename[src_path - src] = 0;
 
             for (i = 1; i < ref->nlvl_from; i++)
-                av_strlcat(filename, "../", 1024);
+                av_strlcat(filename, "../", sizeof(filename));
 
-            av_strlcat(filename, ref->path + l + 1, 1024);
+            av_strlcat(filename, ref->path + l + 1, sizeof(filename));
 
             if (!avio_open2(pb, filename, AVIO_FLAG_READ, int_cb, NULL))
                 return 0;