diff --git a/mpvcore/player/misc.c b/mpvcore/player/misc.c
index 548e2c7967..5f15ca7124 100644
--- a/mpvcore/player/misc.c
+++ b/mpvcore/player/misc.c
@@ -199,7 +199,7 @@ void merge_playlist_files(struct playlist *pl)
             bstr_strip(bstr0(e->filename)).len != strlen(e->filename))
         {
             // %length%
-            edl = talloc_asprintf_append_buffer(edl, "%%%d%%", strlen(e->filename));
+            edl = talloc_asprintf_append_buffer(edl, "%%%zd%%", strlen(e->filename));
         }
         edl = talloc_strdup_append_buffer(edl, e->filename);
     }