diff --git a/Dockerfile b/Dockerfile
index a2e93b423cf..9c6a5113f33 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-# syntax=docker/dockerfile:1.4
+# syntax=docker/dockerfile:1.6
 
 # Note: This file must be kept in sync in ./Dockerfile and ./docker/ubuntu/Dockerfile.
 #       Changes to this file must be copied over to the other file.  
diff --git a/docker/ubuntu/Dockerfile b/docker/ubuntu/Dockerfile
index a2e93b423cf..9c6a5113f33 100644
--- a/docker/ubuntu/Dockerfile
+++ b/docker/ubuntu/Dockerfile
@@ -1,4 +1,4 @@
-# syntax=docker/dockerfile:1.4
+# syntax=docker/dockerfile:1.6
 
 # Note: This file must be kept in sync in ./Dockerfile and ./docker/ubuntu/Dockerfile.
 #       Changes to this file must be copied over to the other file.