diff --git a/r/container_cluster.html.markdown b/r/container_cluster.html.markdown
index b72d5b82..92b18f9d 100644
--- a/r/container_cluster.html.markdown
+++ b/r/container_cluster.html.markdown
@@ -100,10 +100,10 @@ which the cluster's instances are launched
 
 **Master Auth** supports the following arguments:
 
-* `password` - The password to use for HTTP basic authentication when accessing
+* `password` - (Required) The password to use for HTTP basic authentication when accessing
     the Kubernetes master endpoint
 
-* `username` - The username to use for HTTP basic authentication when accessing
+* `username` - (Required) The username to use for HTTP basic authentication when accessing
     the Kubernetes master endpoint
 
 **Node Config** supports the following arguments: