diff --git a/roles/base/tasks/RedHat.yml b/roles/base/tasks/RedHat.yml
index ac02118..a229d47 100644
--- a/roles/base/tasks/RedHat.yml
+++ b/roles/base/tasks/RedHat.yml
@@ -12,7 +12,7 @@
 - name: install postfix
   include_role:
     name: postfix
-  when: "'mail' not in {{ group_names }}"
+  when: "'mail' not in group_names"
 
 - name: install packages
   package: