diff --git a/docs/source/tutorials/render-file.md b/docs/source/tutorials/render-file.md
index f34dc56be1..17c24228ed 100644
--- a/docs/source/tutorials/render-file.md
+++ b/docs/source/tutorials/render-file.md
@@ -85,7 +85,7 @@ var engine = new Liquid({
         existsSync () {
             return true
         },
-        exists () {
+        async exists () {
             return true
         },
         contains () {