diff --git a/functional/tests/identity/v3/test_identity.py b/functional/tests/identity/v3/test_identity.py
index 3f98874..9281f9a 100644
--- a/functional/tests/identity/v3/test_identity.py
+++ b/functional/tests/identity/v3/test_identity.py
@@ -54,6 +54,9 @@ class IdentityTests(test.TestCase):
         if hasattr(super(IdentityTests, cls), 'setUpClass'):
             super(IdentityTests, cls).setUpClass()
 
+        # Backup old environment variables
+        cls._old_env = os.environ
+
         # prepare v3 env
         auth_url = os.environ.get('OS_AUTH_URL')
         auth_url = auth_url.replace('v2.0', 'v3')
@@ -91,6 +94,9 @@ class IdentityTests(test.TestCase):
         cls.openstack('domain set --disable %s' % cls.domain_name)
         cls.openstack('domain delete %s' % cls.domain_name)
 
+        # Restore environment variables
+        os.environ = cls._old_env
+
         if hasattr(super(IdentityTests, cls), 'tearDownClass'):
             super(IdentityTests, cls).tearDownClass()
 
diff --git a/functional/tests/volume/v1/common.py b/functional/tests/volume/v1/common.py
index 7d35ed5..8a4412f 100644
--- a/functional/tests/volume/v1/common.py
+++ b/functional/tests/volume/v1/common.py
@@ -20,4 +20,9 @@ class BaseVolumeTests(test.TestCase):
 
     @classmethod
     def setUpClass(cls):
+        cls._old_env = os.environ
         os.environ['OS_VOLUME_API_VERSION'] = '1'
+
+    @classmethod
+    def tearDownClass(cls):
+        os.environ = cls._old_env
diff --git a/functional/tests/volume/v2/common.py b/functional/tests/volume/v2/common.py
index 8652c2d..a881865 100644
--- a/functional/tests/volume/v2/common.py
+++ b/functional/tests/volume/v2/common.py
@@ -20,4 +20,9 @@ class BaseVolumeTests(test.TestCase):
 
     @classmethod
     def setUpClass(cls):
+        cls._old_env = os.environ
         os.environ['OS_VOLUME_API_VERSION'] = '2'
+
+    @classmethod
+    def tearDownClass(cls):
+        os.environ = cls._old_env