diff --git a/examples/mysql/README.md b/examples/mysql/README.md
index f26cd5d..4180617 100644
--- a/examples/mysql/README.md
+++ b/examples/mysql/README.md
@@ -1,6 +1,7 @@
 # Example: mysql resource based on GCP CloudSQL
 
 ## Configuration
+
 This example configures a [mysql](https://developer.humanitec.com/platform-orchestrator/reference/resource-types/#mysql) Resource Definition using GCP CloudSQL. A workload using the `mysql` resource to create database instance looks like:
 
 ```yaml
@@ -24,7 +25,9 @@ resources:
 ```mermaid
 graph TD;
   subgraph VPC
-    database["MySQl GCP CloudSQL"]
+    subgraph server["MySQL CloudSQL Database Instance"]
+      database["CloudSQL Database"]
+    end
     subgraph GKE Cluster
       pod[workload pod]
     end
@@ -36,10 +39,13 @@ graph TD;
 
 ```mermaid
 graph LR;
-  workload_1 --> db_1["db_1, resource_type: mysql"]
-  workload_2 --> db_2["db_2, resource_type: mysql"]
-  workload_2 --> shared.db_1["shared.db_1, resource_type: mysql"]
-  workload_3 --> shared.db_1["shared.db_1, resource_type: mysql"]  
+    workload_1 --> db_1["db_1, resource_type: mysql"]
+    workload_2 --> db_2["db_2, resource_type: mysql"]
+    workload_2 --> shared.db_1["shared.db_1, resource_type: mysql"]
+    workload_3 --> shared.db_1["shared.db_1, resource_type: mysql"]
+    db_1 --> server["main-mysql, resource_type: mysql-instance"]
+    db_2 --> server
+    shared.db_1 --> server
 ```
 
 <!-- BEGIN_TF_DOCS -->
diff --git a/examples/mysql/main.tf b/examples/mysql/main.tf
index c07f7bf..c02a2b9 100644
--- a/examples/mysql/main.tf
+++ b/examples/mysql/main.tf
@@ -91,14 +91,13 @@ module "mysql_instance" {
 }
 
 resource "humanitec_resource_definition_criteria" "mysql_instance" {
-  resource_definition_id = module.mysql.id
+  resource_definition_id = module.mysql_instance.id
   app_id                 = humanitec_application.example.id
   class                  = local.mysql_instance_class
   res_id                 = local.mysql_instance_res_id
   force_delete           = true
 }
 
-
 module "mysql" {
   source = "../../humanitec-resource-defs/mysql/basic"
 
diff --git a/examples/postgres/README.md b/examples/postgres/README.md
index b307193..7841d4a 100644
--- a/examples/postgres/README.md
+++ b/examples/postgres/README.md
@@ -1,6 +1,7 @@
 # Example: postgres resource based on GCP CloudSQL
 
 ## Configuration
+
 This example configures a [postgres](https://developer.humanitec.com/platform-orchestrator/reference/resource-types/#postgres) Resource Definition using GCP CloudSQL. A workload using the `postgres` resource to create database instance looks like:
 
 ```yaml
diff --git a/modules/cloudsql-instance/basic/main.tf b/modules/cloudsql-instance/basic/main.tf
index 4b06336..04cd3e7 100644
--- a/modules/cloudsql-instance/basic/main.tf
+++ b/modules/cloudsql-instance/basic/main.tf
@@ -2,6 +2,9 @@ locals {
   # Name restrictions https://cloud.google.com/sql/docs/postgres/instance-settings
   # The total length of project-ID:instance-ID must be 98 characters or less.
   default_name = substr("${var.prefix}${var.app_id}-${var.env_id}-${replace(var.res_id, ".", "-")}", 0, 98 - length(var.project))
+
+  # From https://cloud.google.com/sql/docs/mysql/create-edit-iam-instances#configure-iam-db-instance
+  iam_authentication_flag = var.port == 5432 ? "cloudsql.iam_authentication" : "cloudsql_iam_authentication"
 }
 
 resource "google_sql_database_instance" "main" {
@@ -22,7 +25,7 @@ resource "google_sql_database_instance" "main" {
     }
 
     database_flags {
-      name  = "cloudsql.iam_authentication"
+      name  = local.iam_authentication_flag
       value = "on"
     }
   }