diff --git a/beets/util/artresizer.py b/beets/util/artresizer.py
index 8468a6ccc..820bc4ed1 100644
--- a/beets/util/artresizer.py
+++ b/beets/util/artresizer.py
@@ -25,6 +25,7 @@ from tempfile import NamedTemporaryFile
 from six.moves.urllib.parse import urlencode
 from beets import logging
 from beets import util
+import six
 
 # Resizing methods
 PIL = 1
@@ -159,10 +160,9 @@ class Shareable(type):
         return self._instance
 
 
-class ArtResizer(object):
+class ArtResizer(six.with_metaclass(Shareable, object)):
     """A singleton class that performs image resizes.
     """
-    __metaclass__ = Shareable
 
     def __init__(self):
         """Create a resizer object with an inferred method.
diff --git a/beetsplug/metasync/__init__.py b/beetsplug/metasync/__init__.py
index 3fc0be4cc..02f0b0f9b 100644
--- a/beetsplug/metasync/__init__.py
+++ b/beetsplug/metasync/__init__.py
@@ -24,6 +24,7 @@ from importlib import import_module
 from beets.util.confit import ConfigValueError
 from beets import ui
 from beets.plugins import BeetsPlugin
+import six
 
 
 METASYNC_MODULE = 'beetsplug.metasync'
@@ -35,9 +36,7 @@ SOURCES = {
 }
 
 
-class MetaSource(object):
-    __metaclass__ = ABCMeta
-
+class MetaSource(six.with_metaclass(ABCMeta, object)):
     def __init__(self, config, log):
         self.item_types = {}
         self.config = config