diff --git a/vars/main.yml b/vars/main.yml
index b2d84c7..de6764a 100644
--- a/vars/main.yml
+++ b/vars/main.yml
@@ -25,8 +25,8 @@ redmine_pkg_dependencies:
   - imagemagick
 
 redmine_ppa_packages:
-  - 'ruby{{ ruby_ppa_version }}'
-  - 'ruby{{ ruby_ppa_version }}-dev'
+  - "ruby{{ ruby_ppa_version }}"
+  - "ruby{{ ruby_ppa_version }}-dev"
   - rails
   - ruby-rmagick