diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index c84e9a31..03e0479a 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -55,7 +55,7 @@ jobs:
           CERTIFICATE_PATH: ${{ steps.postgres.outputs.certificate-path }}
           EXPECTED_CONNECTION_URI: postgresql://postgres:postgres@localhost:5432/postgres
           EXPECTED_SERVICE_NAME: postgres
-          EXPECTED_SERVER_VERSION: "17"
+          EXPECTED_SERVER_VERSION: "18"
           EXPECTED_SSL: false
 
   parametrized:
@@ -78,6 +78,7 @@ jobs:
           - "14"
           - "15"
           - "16"
+          - "17"
     steps:
       - uses: actions/checkout@v4
 
diff --git a/README.md b/README.md
index b7443eeb..a72da3b9 100644
--- a/README.md
+++ b/README.md
@@ -19,13 +19,13 @@ key features:
 
 #### Inputs
 
-| Key              | Value                                                                              | Default     |
-|------------------|------------------------------------------------------------------------------------|-------------|
-| username         | The username of the user to setup.                                                 | `postgres`  |
-| password         | The password of the user to setup.                                                 | `postgres`  |
-| database         | The database name to setup and grant permissions to created user.                  | `postgres`  |
-| port             | The server port to listen on.                                                      | `5432`      |
-| postgres-version | The PostgreSQL major version to install. Supported values: "14", "15", "16", "17". | `17`        |
+| Key              | Value                                                                                    | Default     |
+|------------------|------------------------------------------------------------------------------------------|-------------|
+| username         | The username of the user to setup.                                                       | `postgres`  |
+| password         | The password of the user to setup.                                                       | `postgres`  |
+| database         | The database name to setup and grant permissions to created user.                        | `postgres`  |
+| port             | The server port to listen on.                                                            | `5432`      |
+| postgres-version | The PostgreSQL major version to install. Supported values: "14", "15", "16", "17", "18". | `18`        |
 
 #### Outputs
 
diff --git a/action.yml b/action.yml
index e90fad2f..e5ebe32e 100644
--- a/action.yml
+++ b/action.yml
@@ -22,8 +22,8 @@ inputs:
     default: "5432"
     required: false
   postgres-version:
-    description: The PostgreSQL major version to install. Either "14", "15", "16" or "17".
-    default: "17"
+    description: The PostgreSQL major version to install. Either "14", "15", "16", "17" or "18".
+    default: "18"
   ssl:
     description: When "true", encrypt connections using SSL (TLS).
     default: "false"
@@ -43,8 +43,8 @@ runs:
   steps:
     - name: Install PostgreSQL
       run: |
-        if [[ ! "${{ inputs.postgres-version }}" =~ ^(14|15|16|17)$ ]]; then
-          echo "::error::postgres-version must be one of: 14, 15, 16, 17."
+        if [[ ! "${{ inputs.postgres-version }}" =~ ^(14|15|16|17|18)$ ]]; then
+          echo "::error::postgres-version must be one of: 14, 15, 16, 17, 18."
           exit 1
         fi