diff --git a/tasks/os-debian.yml b/tasks/os-debian.yml
index b794330..0c92993 100644
--- a/tasks/os-debian.yml
+++ b/tasks/os-debian.yml
@@ -7,7 +7,7 @@
   copy:
     dest: /etc/apt/apt.conf.d/99AutomaticClean
     content: |
-      Aptitude::Clean-After-Install "{{if true == apt_clean_after_install || apt_proxy is defined then 'true' else 'false'}}";
+      Aptitude::Clean-After-Install "{{if true == (apt_clean_after_install|default(false)) || apt_proxy is defined then 'true' else 'false'}}";
     owner: root
     group: root
     mode: 0644