diff --git a/test/test_persistence.py b/test/test_persistence.py
index a29056c..4afa10c 100644
--- a/test/test_persistence.py
+++ b/test/test_persistence.py
@@ -1,3 +1,4 @@
+import os
 import unittest
 from datetime import datetime
 
@@ -9,11 +10,19 @@ from sample_data import TEST_DATA
 class DatabaseTestCase(unittest.TestCase):
 
     def setUp(self):
-        self.db = connect('sqlite:///:memory:')
+        os.environ['DATABASE_URL'] = 'sqlite:///:memory:'
+        self.db = connect()
         self.tbl = self.db['weather']
         for row in TEST_DATA:
             self.tbl.insert(row)
 
+    def tearDown(self):
+        # ensure env variable was unset
+        del os.environ['DATABASE_URL']
+
+    def test_valid_database_url(self):
+        assert self.db.url, os.environ['DATABASE_URL']
+
     def test_tables(self):
         assert self.db.tables == ['weather'], self.db.tables
 
@@ -35,7 +44,7 @@ class DatabaseTestCase(unittest.TestCase):
 class TableTestCase(unittest.TestCase):
 
     def setUp(self):
-        self.db = connect('sqlite:///:memory:')
+        self.db = connect(url='sqlite:///:memory:')
         self.tbl = self.db['weather']
         for row in TEST_DATA:
             self.tbl.insert(row)