diff --git a/tasks/Darwin.yml b/tasks/Darwin.yml
index b870459..0cf1f51 100644
--- a/tasks/Darwin.yml
+++ b/tasks/Darwin.yml
@@ -92,14 +92,14 @@
     deployment_agent_cmd_args: "{{ deployment_agent_cmd_args }} +
       ['--addDeploymentGroupTags', '--deploymentGroupTags \\'{{ az_devops_deployment_group_tags }}\\'']"
   when:
-    - az_devops_deployment_group_tags is defined
+    - az_devops_deployment_group_tags is defined and az_devops_deployment_group_tags != None
 
 - name: Set proxy
   set_fact:
     agent_cmd_args: "{{ agent_cmd_args }} + ['--proxyurl \\'{{ az_devops_proxy_url }}\\'',
       '--proxyusername \\'{{ az_devops_proxy_username }}\\'', '--proxypassword \\'{{ az_devops_proxy_password }}\\'']"
   when:
-    - az_devops_proxy_url is defined
+    - az_devops_proxy_url is defined and az_devops_proxy_url != None
 
 - name: Uninstall agent service
   command: ./svc.sh uninstall
diff --git a/tasks/Linux.yml b/tasks/Linux.yml
index ae60468..ae9a9d6 100644
--- a/tasks/Linux.yml
+++ b/tasks/Linux.yml
@@ -97,13 +97,13 @@
     deployment_agent_cmd_args: "{{ deployment_agent_cmd_args }} +
       ['--addDeploymentGroupTags', '--deploymentGroupTags \\'{{ az_devops_deployment_group_tags }}\\'']"
   when:
-    - az_devops_deployment_group_tags is defined
+    - az_devops_deployment_group_tags is defined and az_devops_deployment_group_tags != None
 
 - name: Set proxy
   set_fact:
     agent_cmd_args: "{{ agent_cmd_args }} + ['--proxyurl \\'{{ az_devops_proxy_url }}\\'', '--proxyusername \\'{{ az_devops_proxy_username }}\\'', '--proxypassword \\'{{ az_devops_proxy_password }}\\'']"
   when:
-    - az_devops_proxy_url is defined
+    - az_devops_proxy_url is defined and az_devops_proxy_url != None
 
 - name: Download and unarchive
   unarchive:
diff --git a/tasks/Windows.yml b/tasks/Windows.yml
index ceaedaa..817f6d9 100644
--- a/tasks/Windows.yml
+++ b/tasks/Windows.yml
@@ -50,25 +50,25 @@
   set_fact:
     deployment_install_options: "{{ deployment_install_options }} + ['/DeploymentGroupTags:{{ az_devops_deployment_group_tags }}']"
   when:
-    - az_devops_deployment_group_tags is defined
+    - az_devops_deployment_group_tags is defined and az_devops_deployment_group_tags != None
 
 - name: Add az_devops_proxy_url
   set_fact:
     common_install_options: "{{ common_install_options }} + ['/ProxyUrl:{{ az_devops_proxy_url }}']"
   when:
-    - az_devops_proxy_url is defined and az_devops_proxy_url
+    - az_devops_proxy_url is defined and az_devops_proxy_url != None
 
 - name: Add az_devops_proxy_username
   set_fact:
     common_install_options: "{{ common_install_options }} + ['/ProxyUserName:{{ az_devops_proxy_username }}']"
   when:
-    - az_devops_proxy_username is defined and az_devops_proxy_username
+    - az_devops_proxy_username is defined and az_devops_proxy_username != None
 
 - name: Add az_devops_proxy_password
   set_fact:
     common_install_options: "{{ common_install_options }} + ['/ProxyPassword:{{ az_devops_proxy_password }}']"
   when:
-    - az_devops_proxy_password is defined and az_devops_proxy_password
+    - az_devops_proxy_password is defined and az_devops_proxy_password != None
 
 - name: Configure agent as a build server
   set_fact: