diff --git a/nova_zvm/tests/unit/virt/zvm/test_driver.py b/nova_zvm/tests/unit/virt/zvm/test_driver.py
index 924c411..8d9019c 100644
--- a/nova_zvm/tests/unit/virt/zvm/test_driver.py
+++ b/nova_zvm/tests/unit/virt/zvm/test_driver.py
@@ -210,13 +210,13 @@ class TestZVMDriver(test.NoDBTestCase):
 
     @mock.patch('nova_zvm.virt.zvm.driver.ZVMDriver.list_instances')
     def test_private_instance_exists_True(self, list_instances):
-        list_instances.return_value = ['vm1', 'vm2']
+        list_instances.return_value = ['VM1', 'VM2']
         res = self.driver._instance_exists('vm1')
         self.assertTrue(res)
 
     @mock.patch('nova_zvm.virt.zvm.driver.ZVMDriver.list_instances')
     def test_private_instance_exists_False(self, list_instances):
-        list_instances.return_value = ['vm1', 'vm2']
+        list_instances.return_value = ['VM1', 'VM2']
         res = self.driver._instance_exists('vm3')
         self.assertFalse(res)
 
@@ -450,7 +450,7 @@ class TestZVMDriver(test.NoDBTestCase):
 
     @mock.patch('nova_zvm.virt.zvm.utils.zVMConnectorRequestHandler.call')
     def test_instance_power_action(self, call):
-        call.side_effect = [['test0001', 'test0002'], None]
+        call.side_effect = [['TEST0001', 'TEST0002'], None]
         self.driver._instance_power_action(self._instance, 'guest_start')
         call.assert_any_call('guest_list')
         call.assert_any_call('guest_start', 'test0001')
diff --git a/nova_zvm/virt/zvm/driver.py b/nova_zvm/virt/zvm/driver.py
index 4737c0e..bebea10 100644
--- a/nova_zvm/virt/zvm/driver.py
+++ b/nova_zvm/virt/zvm/driver.py
@@ -160,7 +160,7 @@ class ZVMDriver(driver.ComputeDriver):
 
     def _instance_exists(self, instance_name):
         """Overwrite this to using instance name as input parameter."""
-        return instance_name in self.list_instances()
+        return instance_name.upper() in self.list_instances()
 
     def instance_exists(self, instance):
         """Overwrite this to using instance name as input parameter."""