diff --git a/tasks/main.yml b/tasks/main.yml
index 359a066..a929037 100644
--- a/tasks/main.yml
+++ b/tasks/main.yml
@@ -6,7 +6,8 @@
 
 - fail:
     msg: 'Invalid `common__iptables__state`: {{ common__iptables__state }}'
-  when: (common__iptables__state != 'purge') and
+  when: (common__iptables__state != null) and
+        (common__iptables__state != 'purge') and
         (common__iptables__state != 'remove') and
         (common__iptables__state != 'install')
 - include_tasks: iptables/purge.yml
@@ -19,7 +20,8 @@
 
 - fail:
     msg: 'Invalid `common__certbot__state`: {{ common__certbot__state }}'
-  when: (common__certbot__state != 'purge') and
+  when: (common__certbot__state != null) and
+        (common__certbot__state != 'purge') and
         (common__certbot__state != 'remove') and
         (common__certbot__state != 'install')
 - include_tasks: certbot/purge.yml
@@ -32,7 +34,8 @@
 
 - fail:
     msg: 'Invalid `common__apache__state`: {{ common__apache__state }}'
-  when: (common__apache__state != 'purge') and
+  when: (common__apache__state != null) and
+        (common__apache__state != 'purge') and
         (common__apache__state != 'remove') and
         (common__apache__state != 'install')
 - include_tasks: apache/purge.yml
@@ -45,7 +48,8 @@
 
 - fail:
     msg: 'Invalid `common__nginx__state`: {{ common__nginx__state }}'
-  when: (common__nginx__state != 'purge') and
+  when: (common__nginx__state != null) and
+        (common__nginx__state != 'purge') and
         (common__nginx__state != 'remove') and
         (common__nginx__state != 'install')
 - include_tasks: nginx/purge.yml