diff --git a/authorizenet/apicontrollersbase.py b/authorizenet/apicontrollersbase.py
index bab6e0f..11fc29d 100644
--- a/authorizenet/apicontrollersbase.py
+++ b/authorizenet/apicontrollersbase.py
@@ -7,6 +7,7 @@
 import logging
 import pyxb
 import sys
+import threading
 import xml.dom.minidom
 import requests
 from lxml import objectify
@@ -75,6 +76,7 @@ class APIOperationBase(APIOperationBaseInterface):
     
     __metaclass__ = abc.ABCMeta 
     __initialized = False
+    __environment_lock = threading.Lock()
     __merchantauthentication = "null"
     __environment = "null"
     
@@ -118,7 +120,12 @@ def getprettyxmlrequest(self):
     
     def execute(self):
         
-        self.endpoint = APIOperationBase.__environment
+        # Read environment at execute time with lock to ensure consistency
+        with APIOperationBase.__environment_lock:
+            # Initialize class environment to SANDBOX if not already set
+            if APIOperationBase.__environment == "null":
+                APIOperationBase.__environment = constants.SANDBOX
+            self.endpoint = APIOperationBase.__environment
               
         anetLogger.debug('Executing http post to url: %s', self.endpoint)
         
@@ -193,8 +200,8 @@ def beforeexecute(self):
         return 
     
     @staticmethod
-    def getmerchantauthentication(self):
-        return self.__merchantauthentication
+    def getmerchantauthentication():
+        return APIOperationBase.__merchantauthentication
     
     @staticmethod
     def setmerchantauthentication(merchantauthentication):
@@ -204,20 +211,22 @@ def setmerchantauthentication(merchantauthentication):
     def validateandsetmerchantauthentication(self):
         anetapirequest = apicontractsv1.ANetApiRequest()
         if (anetapirequest.merchantAuthentication == "null"):
-            if (self.getmerchantauthentication() != "null"):
-                anetapirequest.merchantAuthentication = self.getmerchantauthentication()
+            if (APIOperationBase.getmerchantauthentication() != "null"):
+                anetapirequest.merchantAuthentication = APIOperationBase.getmerchantauthentication()
             else:
                 raise ValueError('Merchant Authentication can not be null')
         return
     
     @staticmethod
-    def getenvironment(self):
-        return APIOperationBase.__environment
+    def getenvironment():
+        with APIOperationBase.__environment_lock:
+            return APIOperationBase.__environment
         
     
     @staticmethod
     def setenvironment(userenvironment):
-        APIOperationBase.__environment = userenvironment 
+        with APIOperationBase.__environment_lock:
+            APIOperationBase.__environment = userenvironment 
         return 
     
     def __init__(self, apiRequest):
@@ -233,9 +242,8 @@ def __init__(self, apiRequest):
             raise ValueError('Input request cannot be null')
          
         self._request = apiRequest
-        __merchantauthentication = apicontractsv1.merchantAuthenticationType()
-        APIOperationBase.__environment = constants.SANDBOX
         
+        __merchantauthentication = apicontractsv1.merchantAuthenticationType()
         APIOperationBase.setmerchantauthentication(__merchantauthentication)
         self.validate()