diff --git a/.travis.yml b/.travis.yml
index c5cef80..6dcf7f8 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -14,6 +14,12 @@ env:
   - TOXENV=py35-djangomaster
   - TOXENV=py36-django111
   - TOXENV=py36-djangomaster
+  # XXX: Use a matrix to build these?
+  - TOXENV=py36-django111-postgres DB=postgres
+  - TOXENV=py36-djangomaster-postgres DB=postgres
+
+services:
+  - postgres
 
 matrix:
   fast_finish: true
@@ -40,6 +46,10 @@ cache:
     - $HOME/.cache/pip
     - $TRAVIS_BUILD_DIR/.tox
 
+before_install:
+- psql -c 'CREATE DATABASE default;' -U postgres || true
+- psql -c 'CREATE DATABASE secondary;' -U postgres || true
+
 install:
   - pip install --upgrade pip wheel setuptools
   - pip install codecov coverage tox
diff --git a/runtests.py b/runtests.py
index f0a1609..fd67216 100755
--- a/runtests.py
+++ b/runtests.py
@@ -2,6 +2,7 @@
 import sys
 from os.path import abspath, dirname
 
+import dj_database_url
 import django
 from django.conf import settings
 from django.core.management import execute_from_command_line
@@ -18,14 +19,14 @@ if not settings.configured:
     settings.configure(
         DEBUG=False,
         DATABASES={
-            'default': {
-                'ENGINE': 'django.db.backends.sqlite3',
-                'NAME': ':memory:'
-            },
-            'secondary': {
-                'ENGINE': 'django.db.backends.sqlite3',
-                'NAME': ':memory:'
-            }
+            'default': dj_database_url.config(
+                env='PRIMARY_DATABASE',
+                default='sqlite://:memory:',
+            ),
+            'secondary': dj_database_url.config(
+                env='SECONDARY_DATABASE',
+                default='sqlite://:memory:',
+            ),
         },
         TEST_RUNNER="django.test.runner.DiscoverRunner",
         INSTALLED_APPS=(
diff --git a/tox.ini b/tox.ini
index b6fc999..f8e95a8 100644
--- a/tox.ini
+++ b/tox.ini
@@ -9,11 +9,15 @@ envlist =
 [testenv]
 setenv =
 	PYTHONWARNINGS = all
+	postgres: DEFAULT_DATABASE = postgres:///default
+	postgres: SECONDARY_DATABASE = postgres:///secondary
 deps =
 	coverage
+	dj-database-url
 	django110: Django >= 1.10, < 1.11
 	django111: Django >= 1.11, < 2.0
 	djangomaster: https://github.com/django/django/archive/master.tar.gz
+	postgres: psycopg2
 commands =
 	coverage run --source polymorphic runtests.py