diff --git a/Dockerfile b/Dockerfile
index 6d49bde..35355ad 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-# syntax=docker/dockerfile:1.20-labs
+# syntax=docker/dockerfile:1.21-labs
 
 # The ARCH can be overridden by providing it a value in the command line
 # with the "--build-arg=XXX" argument fed to 'docker build'.
diff --git a/devel-containers/Dockerfile.devimg b/devel-containers/Dockerfile.devimg
index 3890099..010106a 100644
--- a/devel-containers/Dockerfile.devimg
+++ b/devel-containers/Dockerfile.devimg
@@ -1,4 +1,4 @@
-# syntax=docker/dockerfile:1.20-labs
+# syntax=docker/dockerfile:1.21-labs
 
 # The ARCH can be overridden by providing it a value in the command line
 # with the "--build-arg=XXX" argument fed to 'docker build'.