diff --git a/.github/workflows/tests.yaml b/.github/workflows/tests.yaml
index 52a0e5e..d6faefc 100644
--- a/.github/workflows/tests.yaml
+++ b/.github/workflows/tests.yaml
@@ -11,9 +11,18 @@ jobs:
     runs-on: ubuntu-22.04
     timeout-minutes: 5
 
+    strategy:
+      matrix:
+        postgres-image:
+          - "postgres:12"
+          - "postgres:13"
+          - "postgres:14"
+          - "postgres:15"
+          - "postgres:16"
+
     services:
       postgres:
-        image: postgres
+        image: ${{ matrix.postgres-image }}
         env:
           POSTGRES_PASSWORD: postgres
         options: >-
@@ -24,23 +33,23 @@ jobs:
         ports:
           - 5432:5432
 
-    strategy:
-      matrix:
-        python-version: ["3.10", "3.11", "3.12"]
-
     steps:
       - name: Clone the code
         uses: actions/checkout@v4
 
-      - name: Set up Python ${{ matrix.python-version }}
+      - name: Set up Python versions
         uses: actions/setup-python@v5
         with:
-          python-version: ${{ matrix.python-version }}
+          python-version: |
+            3.12
+            3.11
+            3.10
+          cache: 'pip'
 
-      - name: Install requirements
-        run: make install
+      - name: Install tox
+        run: pip install tox
 
       - name: Run the tests
-        run: tox
+        run: tox --parallel --parallel-no-spinner --skip-missing-interpreters=false
         env:
           DATABASE_URL: postgres://postgres:postgres@localhost/django_integrity
diff --git a/README.md b/README.md
index 7210e83..2437037 100644
--- a/README.md
+++ b/README.md
@@ -9,6 +9,7 @@ This package is tested against:
 
 - Python 3.10, 3.11, or 3.12.
 - Django 4.1, 4.2, or 5.0.
+- PostgreSQL 12 to 16
 
 ## Local development