diff --git a/tempest/api/network/base.py b/tempest/api/network/base.py
index dd888a6..8720985 100644
--- a/tempest/api/network/base.py
+++ b/tempest/api/network/base.py
@@ -53,8 +53,6 @@
 
     # Default to ipv4.
     _ip_version = 4
-    _tenant_network_cidr = CONF.network.tenant_network_cidr
-    _tenant_network_mask_bits = CONF.network.tenant_network_mask_bits
 
     @classmethod
     def setUpClass(cls):
@@ -147,8 +145,12 @@
     def create_subnet(cls, network):
         """Wrapper utility that returns a test subnet."""
         # The cidr and mask_bits depend on the ip version.
-        cidr = netaddr.IPNetwork(cls._tenant_network_cidr)
-        mask_bits = cls._tenant_network_mask_bits
+        if cls._ip_version == 4:
+            cidr = netaddr.IPNetwork(CONF.network.tenant_network_cidr)
+            mask_bits = CONF.network.tenant_network_mask_bits
+        elif cls._ip_version == 6:
+            cidr = netaddr.IPNetwork(CONF.network.tenant_network_v6_cidr)
+            mask_bits = CONF.network.tenant_network_v6_mask_bits
         # Find a cidr that is not in use yet and create a subnet with it
         body = None
         failure = None
diff --git a/tempest/api/network/test_networks.py b/tempest/api/network/test_networks.py
index aba2c8e..654552d 100644
--- a/tempest/api/network/test_networks.py
+++ b/tempest/api/network/test_networks.py
@@ -85,8 +85,12 @@
         updated_net = body['network']
         self.assertEqual(updated_net['name'], new_name)
         # Find a cidr that is not in use yet and create a subnet with it
-        cidr = netaddr.IPNetwork(self._tenant_network_cidr)
-        mask_bits = self._tenant_network_mask_bits
+        if self._ip_version == 4:
+            cidr = netaddr.IPNetwork(CONF.network.tenant_network_cidr)
+            mask_bits = CONF.network.tenant_network_mask_bits
+        elif self._ip_version == 6:
+            cidr = netaddr.IPNetwork(CONF.network.tenant_network_v6_cidr)
+            mask_bits = CONF.network.tenant_network_v6_mask_bits
         for subnet_cidr in cidr.subnet(mask_bits):
             try:
                 resp, body = self.client.create_subnet(
@@ -464,8 +468,6 @@
 
 class NetworksIpV6TestJSON(NetworksTestJSON):
     _ip_version = 6
-    _tenant_network_cidr = CONF.network.tenant_network_v6_cidr
-    _tenant_network_mask_bits = CONF.network.tenant_network_v6_mask_bits
 
     @classmethod
     def setUpClass(cls):