diff --git a/refstack_client/refstack_client.py b/refstack_client/refstack_client.py
index 3f94203..8ca1abe 100755
--- a/refstack_client/refstack_client.py
+++ b/refstack_client/refstack_client.py
@@ -525,13 +525,6 @@ class RefstackClient:
         cmd = [wrapper, 'tempest', 'run']
         if not self.args.parallel:
             cmd.append('--serial')
-        # TODO(mkopec) until refstack-client uses tempest tag which contains
-        # the following change https://review.openstack.org/#/c/641349/
-        # let's hardcode concurrency here, when the change is merged, the
-        # value of concurrency will be set as default in tempest so the
-        # following two lines can be deleted
-        cmd.append('--concurrency')
-        cmd.append('0')
         # If a test list was specified, have it take precedence.
         if self.args.test_list:
             self.logger.info("Normalizing test list...")
diff --git a/refstack_client/tests/unit/test_client.py b/refstack_client/tests/unit/test_client.py
index 6efc51d..7ab4510 100755
--- a/refstack_client/tests/unit/test_client.py
+++ b/refstack_client/tests/unit/test_client.py
@@ -566,8 +566,7 @@ class TestRefstackClient(unittest.TestCase):
 
         mock_popen.assert_called_with(
             ['%s/tools/with_venv.sh' % self.test_path, 'tempest', 'run',
-             '--serial', '--concurrency', '0', '--regex',
-             'tempest.api.compute'],
+             '--serial', '--regex', 'tempest.api.compute'],
             stderr=None
         )
 
@@ -598,8 +597,7 @@ class TestRefstackClient(unittest.TestCase):
         client.test()
         mock_popen.assert_called_with(
             ['%s/tools/with_venv.sh' % self.test_path, 'tempest', 'run',
-             '--serial', '--concurrency', '0', '--regex',
-             'tempest.api.compute'],
+             '--serial', '--regex', 'tempest.api.compute'],
             stderr=None
         )
 
@@ -632,8 +630,7 @@ class TestRefstackClient(unittest.TestCase):
         client.test()
         mock_popen.assert_called_with(
             ['%s/tools/with_venv.sh' % self.test_path, 'tempest', 'run',
-             '--serial', '--concurrency', '0', '--regex',
-             'tempest.api.compute'],
+             '--serial', '--regex', 'tempest.api.compute'],
             stderr=None
         )
 
@@ -679,8 +676,7 @@ class TestRefstackClient(unittest.TestCase):
         # https://review.opendev.org/c/openstack/tempest/+/768583
         mock_popen.assert_called_with(
             ['%s/tools/with_venv.sh' % self.test_path, 'tempest', 'run',
-             '--serial', '--concurrency', '0', '--whitelist_file',
-             '/tmp/some-list'],
+             '--serial', '--whitelist_file', '/tmp/some-list'],
             stderr=None
         )
 
@@ -740,8 +736,7 @@ class TestRefstackClient(unittest.TestCase):
 
         mock_popen.assert_called_with(
             ['%s/tools/with_venv.sh' % self.test_path, 'tempest', 'run',
-             '--serial', '--concurrency', '0', '--regex',
-             'tempest.api.compute'],
+             '--serial', '--regex', 'tempest.api.compute'],
             stderr=None
         )
         # Since '1' is in the next-stream file, we expect the JSON output file