diff --git a/google/resource_container_cluster.go b/google/resource_container_cluster.go
index 2c20ab8c..90a42e26 100644
--- a/google/resource_container_cluster.go
+++ b/google/resource_container_cluster.go
@@ -24,7 +24,7 @@ var (
 				Type:     schema.TypeSet,
 				Optional: true,
 				Computed: true,
-				MaxItems: 10,
+				MaxItems: 20,
 				Elem:     cidrBlockConfig,
 			},
 		},
diff --git a/website/docs/r/container_cluster.html.markdown b/website/docs/r/container_cluster.html.markdown
index a7c5d088..31199113 100644
--- a/website/docs/r/container_cluster.html.markdown
+++ b/website/docs/r/container_cluster.html.markdown
@@ -258,7 +258,7 @@ This block also contains several computed attributes, documented below. If this
 
 The `master_authorized_networks_config` block supports:
 
-* `cidr_blocks` - (Optional) Defines up to 10 external networks that can access
+* `cidr_blocks` - (Optional) Defines up to 20 external networks that can access
     Kubernetes master through HTTPS.
 
 The `master_authorized_networks_config.cidr_blocks` block supports: