diff --git a/.github/workflows/tox.yml b/.github/workflows/tox.yml
index 34a8608..ab1f700 100644
--- a/.github/workflows/tox.yml
+++ b/.github/workflows/tox.yml
@@ -74,8 +74,9 @@ jobs:
           --health-timeout 5s
           --health-retries 5
 
-    # env:
-    #   TOXENV: pg-only
+    env:
+      TOXENV: pg-only
+      DATABASE_URL: postgres://postgres:postgres@postgres:5432/django_anonymiser
 
     steps:
       - name: Check out the repository
@@ -89,4 +90,4 @@ jobs:
       - name: Install and run tox
         run: |
           pip install tox
-          tox -e pg-only
+          tox
diff --git a/pyproject.toml b/pyproject.toml
index b980b3c..bc0cfb3 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -29,9 +29,8 @@ packages = [{ include = "anonymiser" }]
 python = "^3.10"
 django = "^3.2 || ^4.0 || ^5.0"
 
-[tool.poetry.dev-dependencies]
+[tool.poetry.group.dev.dependencies]
 dj-database-url = "*"
-psycopg2-binary = "*"
 black = "*"
 coverage = "*"
 freezegun = "*"
@@ -42,6 +41,11 @@ pytest-cov = "*"
 pytest-django = "*"
 ruff = "*"
 tox = "*"
+# optional - used for testing with Postgres
+psycopg2-binary = { version = "*", optional = true }
+
+[tool.poetry.extras]
+postgres = ["psycopg2-binary"]
 
 [build-system]
 requires = ["poetry>=0.12"]
diff --git a/tests/settings_postgres.py b/tests/settings_postgres.py
index 329b909..42ab6d4 100644
--- a/tests/settings_postgres.py
+++ b/tests/settings_postgres.py
@@ -1,13 +1,11 @@
 from tests.settings import *  # noqa
+from os import getenv
 
+import dj_database_url
+
+DEFAULT_DATABASE_URL = getenv(
+    "DEFAULT_DATABASE_URL",
+    "postgres://postgres@localhost:5432/django_anonymiser",
+)
 # NB this is obviously not a secure password, but it's only for testing
-DATABASES = {
-    "default": {
-        "ENGINE": "django.db.backends.postgresql",
-        "NAME": "django_anonymiser",
-        "USER": "postgres",
-        "PASSWORD": "postgres",
-        "HOST": "localhost",
-        "PORT": "5432",
-    }
-}
+DATABASES["default"] = dj_database_url.parse(DEFAULT_DATABASE_URL)  # noqa: F405
diff --git a/tox.ini b/tox.ini
index dfb035b..7dd0546 100644
--- a/tox.ini
+++ b/tox.ini
@@ -24,6 +24,7 @@ commands =
 
 [testenv:pg-only]
 deps =
+    dj_database_url
     pytest
     pytest-django
     psycopg2-binary