--- a/etherlab/EthercatMaster.py	Sat Sep 29 16:39:25 2018 +0300
+++ b/etherlab/EthercatMaster.py	Sat Sep 29 16:40:56 2018 +0300
@@ -225,7 +225,7 @@
 ProcessVariablesParser = GenerateParserFromXSDstring(ProcessVariablesXSD)
 
 
-class _EthercatCTN:
+class _EthercatCTN(object):
 
     CTNChildrenTypes = [("EthercatSlave", _EthercatSlaveCTN, "Ethercat Slave")]
     if HAS_MCL: