diff --git a/lower-constraints.txt b/lower-constraints.txt
index 42e0585..056fa65 100644
--- a/lower-constraints.txt
+++ b/lower-constraints.txt
@@ -9,6 +9,5 @@ openstackdocstheme==1.20.0
 openstacksdk==0.31.1
 oslotest==3.2.0
 reno==2.5.0
-six==1.10.0
 Sphinx==1.8.0
 stestr==1.0.0
diff --git a/oslo_limit/limit.py b/oslo_limit/limit.py
index cd3d666..ad7de98 100644
--- a/oslo_limit/limit.py
+++ b/oslo_limit/limit.py
@@ -17,7 +17,6 @@ from keystoneauth1 import loading
 from openstack import connection
 from oslo_config import cfg
 from oslo_log import log
-import six
 
 from oslo_limit import exception
 from oslo_limit import opts
@@ -110,7 +109,7 @@ class Enforcer(object):
 
         :raises exception.ClaimExceedsLimit: when over limits
         """
-        if not project_id or not isinstance(project_id, six.string_types):
+        if not project_id or not isinstance(project_id, str):
             msg = 'project_id must be a non-empty string.'
             raise ValueError(msg)
         if not isinstance(deltas, dict) or len(deltas) == 0:
@@ -118,7 +117,7 @@ class Enforcer(object):
             raise ValueError(msg)
 
         for k, v in deltas.items():
-            if not isinstance(k, six.string_types):
+            if not isinstance(k, str):
                 raise ValueError('resource name is not a string.')
             elif not isinstance(v, int):
                 raise ValueError('resource limit is not an integer.')
diff --git a/requirements.txt b/requirements.txt
index 18e6e7f..f523f83 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -2,7 +2,6 @@
 # of appearance. Changing the order has an impact on the overall integration
 # process, which may cause wedges in the gate later.
 keystoneauth1>=3.9.0 # Apache-2.0
-six>=1.10.0 # MIT
 oslo.config>=5.2.0 # Apache-2.0
 oslo.i18n>=3.15.3 # Apache-2.0
 oslo.log>=3.44.0 # Apache-2.0