diff --git a/openstackclient/api/auth.py b/openstackclient/api/auth.py
index 66272e4247..442873188e 100644
--- a/openstackclient/api/auth.py
+++ b/openstackclient/api/auth.py
@@ -106,7 +106,7 @@ def select_auth_plugin(options):
         # The ultimate default is similar to the original behaviour,
         # but this time with version discovery
         auth_plugin_name = 'osc_password'
-    LOG.debug("Auth plugin %s selected" % auth_plugin_name)
+    LOG.debug("Auth plugin %s selected", auth_plugin_name)
     return auth_plugin_name
 
 
@@ -130,7 +130,7 @@ def build_auth_params(auth_plugin_name, cmd_options):
         auth_plugin_class = None
         plugin_options = set([o.replace('-', '_') for o in get_options_list()])
         for option in plugin_options:
-            LOG.debug('fetching option %s' % option)
+            LOG.debug('fetching option %s', option)
             auth_params[option] = getattr(cmd_options.auth, option, None)
     return (auth_plugin_class, auth_params)
 
diff --git a/openstackclient/api/auth_plugin.py b/openstackclient/api/auth_plugin.py
index deddfcc48f..cff0b75dc9 100644
--- a/openstackclient/api/auth_plugin.py
+++ b/openstackclient/api/auth_plugin.py
@@ -97,7 +97,7 @@ class OSCGenericPassword(ksc_password.Password):
                 ver_u.query,
                 ver_u.fragment,
             ))
-            LOG.debug('Version URL updated: %s' % url)
+            LOG.debug('Version URL updated: %s', url)
 
         return super(OSCGenericPassword, self).create_plugin(
             session=session,
diff --git a/openstackclient/common/clientmanager.py b/openstackclient/common/clientmanager.py
index dce1972515..5696b9e1bc 100644
--- a/openstackclient/common/clientmanager.py
+++ b/openstackclient/common/clientmanager.py
@@ -167,8 +167,8 @@ class ClientManager(object):
         elif 'tenant_name' in self._auth_params:
             self._project_name = self._auth_params['tenant_name']
 
-        LOG.info('Using auth plugin: %s' % self.auth_plugin_name)
-        LOG.debug('Using parameters %s' %
+        LOG.info('Using auth plugin: %s', self.auth_plugin_name)
+        LOG.debug('Using parameters %s',
                   strutils.mask_password(self._auth_params))
         self.auth = auth_plugin.load_from_options(**self._auth_params)
         # needed by SAML authentication
diff --git a/openstackclient/compute/client.py b/openstackclient/compute/client.py
index 23a4decaab..1481ed6535 100644
--- a/openstackclient/compute/client.py
+++ b/openstackclient/compute/client.py
@@ -42,7 +42,7 @@ def make_client(instance):
     else:
         version = instance._api_version[API_NAME]
 
-    LOG.debug('Instantiating compute client for V%s' % version)
+    LOG.debug('Instantiating compute client for V%s', version)
 
     # Set client http_log_debug to True if verbosity level is high enough
     http_log_debug = utils.get_effective_log_level() <= logging.DEBUG