diff --git a/website/docs/r/application_gateway.html.markdown b/website/docs/r/application_gateway.html.markdown
index 7d65240bd39e..4f9a357ddf4d 100644
--- a/website/docs/r/application_gateway.html.markdown
+++ b/website/docs/r/application_gateway.html.markdown
@@ -252,7 +252,7 @@ A `frontend_ip_configuration` block supports the following:
 
 * `name` - (Required) The name of the Frontend IP Configuration.
 
-* `subnet_id` - (Required) The ID of the Subnet which the Application Gateway should be connected to.
+* `subnet_id` - (Optional) The ID of the Subnet.
 
 * `private_ip_address` - (Optional) The Private IP Address to use for the Application Gateway.
 
@@ -276,7 +276,7 @@ A `gateway_ip_configuration` block supports the following:
 
 * `name` - (Required) The Name of this Gateway IP Configuration.
 
-* `subnet_id` - (Required) The ID of a Subnet.
+* `subnet_id` - (Required) The ID of the Subnet which the Application Gateway should be connected to.
 
 ---