diff --git a/iotedgedev/compat.py b/iotedgedev/compat.py
index 1a68c7a3..41c350d6 100644
--- a/iotedgedev/compat.py
+++ b/iotedgedev/compat.py
@@ -2,4 +2,4 @@
 
 PY35 = sys.version_info >= (3, 5)
 PY3 = sys.version_info >= (3, 0)
-PY2 = sys.version_info < (3, 0)
\ No newline at end of file
+PY2 = sys.version_info < (3, 0)
diff --git a/iotedgedev/containerregistry.py b/iotedgedev/containerregistry.py
index 94e6bf1a..40465094 100644
--- a/iotedgedev/containerregistry.py
+++ b/iotedgedev/containerregistry.py
@@ -3,5 +3,3 @@ def __init__(self, server, username, password):
         self.server = server
         self.username = username
         self.password = password
-
-    
\ No newline at end of file
diff --git a/iotedgedev/dockercls.py b/iotedgedev/dockercls.py
index e65e5bd2..8c4ec9dd 100644
--- a/iotedgedev/dockercls.py
+++ b/iotedgedev/dockercls.py
@@ -129,14 +129,14 @@ def setup_registry(self):
 
     def setup_registry_in_config(self, image_names):
         self.output.info(
-            "Replacing 'microsoft/' with '{CONTAINER_REGISTRY_SERVER}/' in config files.")
+            "Replacing 'mcr.microsoft.com/' with '{CONTAINER_REGISTRY_SERVER}/' in config files.")
 
-        # Replace microsoft/ with ${CONTAINER_REGISTRY_SERVER}
+        # Replace mcr.microsoft.com/ with ${CONTAINER_REGISTRY_SERVER}
         for config_file in self.utility.get_config_files():
             config_file_contents = self.utility.get_file_contents(config_file)
             for image_name in image_names:
                 config_file_contents = config_file_contents.replace(
-                    "microsoft/" + image_name, "${CONTAINER_REGISTRY_SERVER}/" + image_name)
+                    "mcr.microsoft.com/" + image_name, "${CONTAINER_REGISTRY_SERVER}/" + image_name)
 
             with open(config_file, "w") as config_file_build:
                 config_file_build.write(config_file_contents)
diff --git a/iotedgedev/envvars.py b/iotedgedev/envvars.py
index 956fdf8a..1b45f6b5 100644
--- a/iotedgedev/envvars.py
+++ b/iotedgedev/envvars.py
@@ -1,14 +1,13 @@
 import os
 import platform
-import socket
 import sys
 from shutil import copyfile
-from .compat import PY2
 
 from dotenv import load_dotenv, set_key
 from fstrings import f
 
 from .args import Args
+from .compat import PY2
 from .connectionstring import DeviceConnectionString, IoTHubConnectionString
 from .containerregistry import ContainerRegistry