diff --git a/castellan/common/utils.py b/castellan/common/utils.py
index 5a7d87ab..7340ea48 100644
--- a/castellan/common/utils.py
+++ b/castellan/common/utils.py
@@ -31,55 +31,55 @@ LOG = logging.getLogger(__name__)
 
 credential_opts = [
     # auth_type opt
-    cfg.StrOpt('auth_type', default=None,
+    cfg.StrOpt('auth_type',
                help="The type of authentication credential to create. "
                "Possible values are 'token', 'password', 'keystone_token', "
                "and 'keystone_password'. Required if no context is passed to "
                "the credential factory."),
 
     # token opt
-    cfg.StrOpt('token', default=None, secret=True,
+    cfg.StrOpt('token', secret=True,
                help="Token for authentication. Required for 'token' and "
                "'keystone_token' auth_type if no context is passed to the "
                "credential factory."),
 
     # password opts
-    cfg.StrOpt('username', default=None,
+    cfg.StrOpt('username',
                help="Username for authentication. Required for 'password' "
                "auth_type. Optional for the 'keystone_password' auth_type."),
-    cfg.StrOpt('password', default=None, secret=True,
+    cfg.StrOpt('password', secret=True,
                help="Password for authentication. Required for 'password' and "
                "'keystone_password' auth_type."),
 
     # keystone credential opts
-    cfg.StrOpt('user_id', default=None,
+    cfg.StrOpt('user_id',
                help="User ID for authentication. Optional for "
                "'keystone_token' and 'keystone_password' auth_type."),
-    cfg.StrOpt('user_domain_id', default=None,
+    cfg.StrOpt('user_domain_id',
                help="User's domain ID for authentication. Optional for "
                "'keystone_token' and 'keystone_password' auth_type."),
-    cfg.StrOpt('user_domain_name', default=None,
+    cfg.StrOpt('user_domain_name',
                help="User's domain name for authentication. Optional for "
                "'keystone_token' and 'keystone_password' auth_type."),
-    cfg.StrOpt('trust_id', default=None,
+    cfg.StrOpt('trust_id',
                help="Trust ID for trust scoping. Optional for "
                "'keystone_token' and 'keystone_password' auth_type."),
-    cfg.StrOpt('domain_id', default=None,
+    cfg.StrOpt('domain_id',
                help="Domain ID for domain scoping. Optional for "
                "'keystone_token' and 'keystone_password' auth_type."),
-    cfg.StrOpt('domain_name', default=None,
+    cfg.StrOpt('domain_name',
                help="Domain name for domain scoping. Optional for "
                "'keystone_token' and 'keystone_password' auth_type."),
-    cfg.StrOpt('project_id', default=None,
+    cfg.StrOpt('project_id',
                help="Project ID for project scoping. Optional for "
                "'keystone_token' and 'keystone_password' auth_type."),
-    cfg.StrOpt('project_name', default=None,
+    cfg.StrOpt('project_name',
                help="Project name for project scoping. Optional for "
                "'keystone_token' and 'keystone_password' auth_type."),
-    cfg.StrOpt('project_domain_id', default=None,
+    cfg.StrOpt('project_domain_id',
                help="Project's domain ID for project. Optional for "
                "'keystone_token' and 'keystone_password' auth_type."),
-    cfg.StrOpt('project_domain_name', default=None,
+    cfg.StrOpt('project_domain_name',
                help="Project's domain name for project. Optional for "
                "'keystone_token' and 'keystone_password' auth_type."),
     cfg.BoolOpt('reauthenticate', default=True,