diff --git a/src/python/m5/SimObject.py b/src/python/m5/SimObject.py
index b76db5c319..32ac7d1ddc 100644
--- a/src/python/m5/SimObject.py
+++ b/src/python/m5/SimObject.py
@@ -40,6 +40,7 @@
 
 from __future__ import print_function
 from __future__ import absolute_import
+from six import add_metaclass
 import six
 if six.PY3:
     long = int
@@ -1073,10 +1074,10 @@ class SimObjectCliWrapper(object):
 # The SimObject class is the root of the special hierarchy.  Most of
 # the code in this class deals with the configuration hierarchy itself
 # (parent/child node relationships).
+@add_metaclass(MetaSimObject)
 class SimObject(object):
     # Specify metaclass.  Any class inheriting from SimObject will
     # get this metaclass.
-    __metaclass__ = MetaSimObject
     type = 'SimObject'
     abstract = True
 
diff --git a/src/python/m5/params.py b/src/python/m5/params.py
index 3593f95bbc..2ea614e95a 100644
--- a/src/python/m5/params.py
+++ b/src/python/m5/params.py
@@ -55,6 +55,7 @@
 #####################################################################
 
 from __future__ import print_function
+from six import add_metaclass
 import six
 if six.PY3:
     long = int
@@ -87,15 +88,17 @@ allParams = {}
 class MetaParamValue(type):
     def __new__(mcls, name, bases, dct):
         cls = super(MetaParamValue, mcls).__new__(mcls, name, bases, dct)
-        assert name not in allParams
+        if name in allParams:
+            warn("%s already exists in allParams. This may be caused by the " \
+                 "Python 2.7 compatibility layer." % (name, ))
         allParams[name] = cls
         return cls
 
 
 # Dummy base class to identify types that are legitimate for SimObject
 # parameters.
+@add_metaclass(MetaParamValue)
 class ParamValue(object):
-    __metaclass__ = MetaParamValue
     cmd_line_settable = False
 
     # Generate the code needed as a prerequisite for declaring a C++
@@ -233,8 +236,8 @@ class ParamDesc(object):
 # that the value is a vector (list) of the specified type instead of a
 # single value.
 
+@add_metaclass(MetaParamValue)
 class VectorParamValue(list):
-    __metaclass__ = MetaParamValue
     def __setattr__(self, attr, value):
         raise AttributeError("Not allowed to set %s on '%s'" % \
                              (attr, type(self).__name__))
@@ -585,8 +588,8 @@ class CheckedIntType(MetaParamValue):
 # class is subclassed to generate parameter classes with specific
 # bounds.  Initialization of the min and max bounds is done in the
 # metaclass CheckedIntType.__init__.
+@add_metaclass(CheckedIntType)
 class CheckedInt(NumericParamValue):
-    __metaclass__ = CheckedIntType
     cmd_line_settable = True
 
     def _check(self):
@@ -1294,7 +1297,6 @@ allEnums = {}
 # Metaclass for Enum types
 class MetaEnum(MetaParamValue):
     def __new__(mcls, name, bases, dict):
-        assert name not in allEnums
 
         cls = super(MetaEnum, mcls).__new__(mcls, name, bases, dict)
         allEnums[name] = cls
@@ -1445,8 +1447,8 @@ module_init(py::module &m_internal)
 
 
 # Base class for enum types.
+@add_metaclass(MetaEnum)
 class Enum(ParamValue):
-    __metaclass__ = MetaEnum
     vals = []
     cmd_line_settable = True
 
@@ -1499,8 +1501,8 @@ class Enum(ParamValue):
         return self.value
 
 # This param will generate a scoped c++ enum and its python bindings.
+@add_metaclass(MetaEnum)
 class ScopedEnum(Enum):
-    __metaclass__ = MetaEnum
     vals = []
     cmd_line_settable = True
 
@@ -1787,8 +1789,8 @@ class MemoryBandwidth(float,ParamValue):
 # make_param_value() above that lets these be assigned where a
 # SimObject is required.
 # only one copy of a particular node
+@add_metaclass(Singleton)
 class NullSimObject(object):
-    __metaclass__ = Singleton
     _name = 'Null'
 
     def __call__(cls):
@@ -2155,9 +2157,8 @@ VectorSlavePort = VectorResponsePort
 # 'Fake' ParamDesc for Port references to assign to the _pdesc slot of
 # proxy objects (via set_param_desc()) so that proxy error messages
 # make sense.
+@add_metaclass(Singleton)
 class PortParamDesc(object):
-    __metaclass__ = Singleton
-
     ptype_str = 'Port'
     ptype = Port
 
diff --git a/src/python/m5/util/code_formatter.py b/src/python/m5/util/code_formatter.py
index 8d48d0f766..9870430d63 100644
--- a/src/python/m5/util/code_formatter.py
+++ b/src/python/m5/util/code_formatter.py
@@ -25,6 +25,7 @@
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 from __future__ import print_function
+from six import add_metaclass
 
 try:
     import builtins
@@ -112,9 +113,8 @@ class code_formatter_meta(type):
                 }
         cls.pattern = re.compile(pat, re.VERBOSE | re.DOTALL | re.MULTILINE)
 
+@add_metaclass(code_formatter_meta)
 class code_formatter(object):
-    __metaclass__ = code_formatter_meta
-
     delim = r'$'
     ident = r'[_A-z]\w*'
     pos = r'[0-9]+'
diff --git a/src/python/m5/util/pybind.py b/src/python/m5/util/pybind.py
index f165044289..18df3bb60c 100644
--- a/src/python/m5/util/pybind.py
+++ b/src/python/m5/util/pybind.py
@@ -35,12 +35,12 @@
 
 from __future__ import print_function
 from __future__ import absolute_import
+from six import add_metaclass
 
 from abc import *
 
+@add_metaclass(ABCMeta)
 class PyBindExport(object):
-    __metaclass__ = ABCMeta
-
     @abstractmethod
     def export(self, code, cname):
         pass