diff --git a/modoboa/core/password_hashers/__init__.py b/modoboa/core/password_hashers/__init__.py
index 80a5a8529..661251784 100644
--- a/modoboa/core/password_hashers/__init__.py
+++ b/modoboa/core/password_hashers/__init__.py
@@ -36,7 +36,7 @@ def get_dovecot_schemes():
     """Return schemes supported by dovecot"""
     supported_schemes = None
     try:
-        code, schemes = doveadm_cmd("pw -l")
+        _, schemes = doveadm_cmd("pw -l")
     except OSError:
         pass
     else:
diff --git a/modoboa/core/password_hashers/base.py b/modoboa/core/password_hashers/base.py
index 88652de13..ccf2f9f2d 100644
--- a/modoboa/core/password_hashers/base.py
+++ b/modoboa/core/password_hashers/base.py
@@ -17,8 +17,27 @@ from random import Random
 from django.utils.crypto import constant_time_compare
 from django.utils.encoding import force_bytes, force_text
 
+from six import with_metaclass
 
-class PasswordHasher(object):
+
+class MetaHasher(type):
+    """
+    PasswordHasher Metaclass
+    
+    Allow classmethod to be properties
+    """
+    @property
+    def name(cls):
+        """Returns the name of the hasher"""
+        return cls.__name__.rstrip('Hasher').lower()
+
+    @property
+    def label(cls):
+        """Returns the label of the hasher"""
+        return cls.name if not cls._weak else "{} (weak)".format(cls.name)
+
+
+class PasswordHasher(with_metaclass(MetaHasher, object)):
     """
     Base class of all hashers.
     """
@@ -27,16 +46,6 @@ class PasswordHasher(object):
     def __init__(self, target="local"):
         self._target = target
 
-    class __metaclass__(type):
-        """class properties"""
-        @property
-        def name(cls):
-            return cls.__name__.rstrip('Hasher').lower()
-
-        @property
-        def label(cls):
-            return cls.name if not cls._weak else "{} (weak)".format(cls.name)
-
     def _encrypt(self, clearvalue, salt=None):
         raise NotImplementedError
 
diff --git a/modoboa/lib/sysutils.py b/modoboa/lib/sysutils.py
index a363643fc..868eddcf8 100644
--- a/modoboa/lib/sysutils.py
+++ b/modoboa/lib/sysutils.py
@@ -46,7 +46,8 @@ def exec_cmd(cmd, sudo_user=None, pinput=None, capture_output=True, **kwargs):
     return process.returncode, output
 
 
-def doveadm_cmd(params, sudo_user=None, pinput=None, capture_output=True, **kwargs):
+def doveadm_cmd(params, sudo_user=None, pinput=None,
+        capture_output=True, **kwargs):
     """Execute doveadm command.
 
     Run doveadm command using the current user. Set :keyword:`sudo_user` if