diff --git a/Dockerfile b/Dockerfile
index 2b1a085..94cec48 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-# syntax=docker/dockerfile:1.20.0
+# syntax=docker/dockerfile:1.21.0
 # check=skip=all
 
 FROM glanceapp/glance:latest