diff --git a/pyagentx/agent.py b/pyagentx/agent.py
index b6c0e2a..a989f7e 100644
--- a/pyagentx/agent.py
+++ b/pyagentx/agent.py
@@ -11,8 +11,7 @@ def emit(self, record):
 # --------------------------------------------
 
 import time
-import Queue
-import inspect
+import queue as Queue
 
 import pyagentx
 from pyagentx.updater import Updater
@@ -31,7 +30,7 @@ def __init__(self):
         self._threads = []
 
     def register(self, oid, class_, freq=10):
-        if Updater not in inspect.getmro(class_):
+        if Updater not in class_.__bases__:
             raise AgentError('Class given isn\'t an updater')
         # cleanup and test oid
         try:
diff --git a/pyagentx/network.py b/pyagentx/network.py
index 9711398..1a70311 100644
--- a/pyagentx/network.py
+++ b/pyagentx/network.py
@@ -13,7 +13,7 @@ def emit(self, record):
 import socket
 import time
 import threading
-import Queue
+import queue as Queue
 
 import pyagentx
 from pyagentx.pdu import PDU
@@ -84,16 +84,16 @@ def _get_updates(self):
                 update_oid = item['oid']
                 update_data = item['data']
                 # clear values with prefix oid
-                for oid in self.data.keys():
+                for oid in list(self.data.keys()):
                     if oid.startswith(update_oid):
                         del(self.data[oid])
                 # insert updated value
-                for row in update_data.values():
+                for row in list(update_data.values()):
                     oid = "%s.%s" % (update_oid, row['name'])
                     self.data[oid] = {'name': oid, 'type':row['type'],
                                       'value':row['value']}
                 # recalculate reverse index if data changed
-                self.data_idx = sorted(self.data.keys(), key=lambda k: tuple(int(part) for part in k.split('.')))
+                self.data_idx = sorted(list(self.data.keys()), key=lambda k: tuple(int(part) for part in k.split('.')))
             except Queue.Empty:
                 break
 
@@ -221,17 +221,17 @@ def _start_network(self):
 
 
             elif request.type == pyagentx.AGENTX_COMMITSET_PDU:
-                for handler in self._sethandlers.values():
+                for handler in list(self._sethandlers.values()):
                     handler.network_commit(request.session_id, request.transaction_id)
                 logger.info("Received COMMITSET PDU")
 
             elif request.type == pyagentx.AGENTX_UNDOSET_PDU:
-                for handler in self._sethandlers.values():
+                for handler in list(self._sethandlers.values()):
                     handler.network_undo(request.session_id, request.transaction_id)
                 logger.info("Received UNDOSET PDU")
 
             elif request.type == pyagentx.AGENTX_CLEANUPSET_PDU:
-                for handler in self._sethandlers.values():
+                for handler in list(self._sethandlers.values()):
                     handler.network_cleanup(request.session_id, request.transaction_id)
                 logger.info("Received CLEANUP PDU")
 
diff --git a/pyagentx/pdu.py b/pyagentx/pdu.py
index 0af8e82..9d62c73 100644
--- a/pyagentx/pdu.py
+++ b/pyagentx/pdu.py
@@ -69,9 +69,10 @@ def encode_oid(self, oid, include=0):
 
     def encode_octet(self, octet):
         buf = struct.pack('!L', len(octet))
-        buf += str(octet)
+        buf += octet
         padding = ( 4 - ( len(octet) % 4 ) ) % 4
-        buf += chr(0)* padding
+        # buf += chr(0)* padding
+        buf += b'0' * padding
         return buf
 
 
@@ -107,14 +108,14 @@ def encode_header(self, pdu_type, payload_length=0, flags=0):
 
 
     def encode(self):
-        buf = ''
+        buf = b''
         if self.type == pyagentx.AGENTX_OPEN_PDU:
             # timeout
             buf += struct.pack('!BBBB', 5, 0, 0, 0)
             # agent OID
             buf += struct.pack('!L', 0)
             # Agent Desc
-            buf += self.encode_octet('MyAgent')
+            buf += self.encode_octet(b'MyAgent')
 
         elif self.type == pyagentx.AGENTX_PING_PDU:
             # No extra data
@@ -169,7 +170,7 @@ def decode_oid(self):
                 sub_ids.append(t[0])
             oid = '.'.join(str(i) for i in sub_ids)
             return oid, ret['include']
-        except Exception, e:
+        except Exception as e:
             logger.exception('Invalid packing OID header')
             logger.debug('%s' % pprint.pformat(self.decode_buf))
 
@@ -196,7 +197,7 @@ def decode_octet(self):
             buf = self.decode_buf[:l]
             self.decode_buf = self.decode_buf[l+padding:]
             return buf
-        except Exception, e:
+        except Exception as e:
             logger.exception('Invalid packing octet header')
 
 
@@ -204,7 +205,7 @@ def decode_value(self):
         try:
             vtype,_ = struct.unpack('!HH', self.decode_buf[:4])
             self.decode_buf = self.decode_buf[4:]
-        except Exception, e:
+        except Exception as e:
             logger.exception('Invalid packing value header')
         oid,_ = self.decode_oid()
         if vtype in [pyagentx.TYPE_INTEGER, pyagentx.TYPE_COUNTER32, pyagentx.TYPE_GAUGE32, pyagentx.TYPE_TIMETICKS]:
@@ -252,7 +253,7 @@ def decode_header(self):
                 context = self.decode_octet() 
                 logger.debug('Context: %s' % context)
             return ret
-        except Exception, e:
+        except Exception as e:
             logger.exception('Invalid packing: %d' % len(self.decode_buf))
             logger.debug('%s' % pprint.pformat(self.decode_buf))
 
diff --git a/pyagentx/updater.py b/pyagentx/updater.py
index 5fb06d4..803d765 100644
--- a/pyagentx/updater.py
+++ b/pyagentx/updater.py
@@ -12,7 +12,7 @@ def emit(self, record):
 
 import time
 import threading
-import Queue
+import queue as Queue
 
 import pyagentx