diff --git a/tasks/main.yml b/tasks/main.yml
index 006adbd..813b5b6 100644
--- a/tasks/main.yml
+++ b/tasks/main.yml
@@ -2,6 +2,27 @@
 - name: Include OS-specific variables.
   include_vars: "{{ ansible_os_family }}.yml"
 
+- name: Define PHP variables.
+  set_fact: "{{ item.key }}={{ hostvars[inventory_hostname][item.value] }}"
+  when:
+    - hostvars[inventory_hostname][item.key] is undefined
+    - hostvars[inventory_hostname][item.value] is defined
+  with_dict:
+    php_conf_paths: __php_conf_paths
+    php_extension_conf_paths: __php_extension_conf_paths
+    php_fpm_daemon: __php_fpm_daemon
+    php_fpm_conf_path: __php_fpm_conf_path
+    php_fpm_pool_conf_path: __php_fpm_pool_conf_path
+    php_mysql_package: __php_mysql_package
+    php_redis_package: __php_redis_package
+    php_memcached_package: __php_memcached_package
+    php_pgsql_package: __php_pgsql_package
+    php_tideways_module_path: __php_tideways_module_path
+    php_uploadprogress_module_path: __php_uploadprogress_module_path
+    php_xdebug_module_path: __php_xdebug_module_path
+    php_xhprof_module_path: __php_xhprof_module_path
+    php_packages: __php_packages
+
 # Setup tasks.
 - include: "setup-{{ ansible_os_family }}.yml"
   static: no
diff --git a/vars/Debian.yml b/vars/Debian.yml
index 424c8c6..3c72547 100644
--- a/vars/Debian.yml
+++ b/vars/Debian.yml
@@ -1,27 +1,27 @@
 ---
 # Configure PHP paths and packages for PHP 5.6 and PHP 7.0.
-php_conf_paths:
+__php_conf_paths:
   - "/etc/php/{{ php_version }}/fpm"
   - "/etc/php/{{ php_version }}/apache2"
   - "/etc/php/{{ php_version }}/cli"
-php_extension_conf_paths:
+__php_extension_conf_paths:
   - "/etc/php/{{ php_version }}/fpm/conf.d"
   - "/etc/php/{{ php_version }}/apache2/conf.d"
   - "/etc/php/{{ php_version }}/cli/conf.d"
-php_fpm_daemon: "php{{ php_version }}-fpm"
-php_fpm_conf_path: "/etc/php/{{ php_version }}/fpm"
-php_fpm_pool_conf_path: "{{ php_fpm_conf_path }}/pool.d/www.conf"
-php_mysql_package: "php{{ php_version }}-mysql"
-php_redis_package: "php{{ php_version }}-redis"
-php_memcached_package: "php{{ php_version }}-memcached"
-php_pgsql_package: "php{{ php_version }}-pgsql"
+__php_fpm_daemon: "php{{ php_version }}-fpm"
+__php_fpm_conf_path: "/etc/php/{{ php_version }}/fpm"
+__php_fpm_pool_conf_path: "{{ php_fpm_conf_path }}/pool.d/www.conf"
+__php_mysql_package: "php{{ php_version }}-mysql"
+__php_redis_package: "php{{ php_version }}-redis"
+__php_memcached_package: "php{{ php_version }}-memcached"
+__php_pgsql_package: "php{{ php_version }}-pgsql"
 
-php_tideways_module_path: "/usr/lib/php/{{ php_version }}/modules"
-php_uploadprogress_module_path: "/usr/lib/php/{{ php_version }}/modules"
-php_xdebug_module_path: "/usr/lib/php/{{ php_version }}/modules"
-php_xhprof_module_path: "/usr/lib/php/{{ php_version }}/modules"
+__php_tideways_module_path: "/usr/lib/php/{{ php_version }}/modules"
+__php_uploadprogress_module_path: "/usr/lib/php/{{ php_version }}/modules"
+__php_xdebug_module_path: "/usr/lib/php/{{ php_version }}/modules"
+__php_xhprof_module_path: "/usr/lib/php/{{ php_version }}/modules"
 
-php_packages:
+__php_packages:
   - "php{{ php_version }}"
   - "php{{ php_version }}-apcu"
   - "php{{ php_version }}-cli"
diff --git a/vars/RedHat.yml b/vars/RedHat.yml
index bca09b4..568eaf6 100644
--- a/vars/RedHat.yml
+++ b/vars/RedHat.yml
@@ -1,5 +1,5 @@
 ---
-php_tideways_module_path: "/usr/lib64/php{{ php_version }}/modules"
-php_uploadprogress_module_path: "/usr/lib64/php{{ php_version }}/modules"
-php_xdebug_module_path: "/usr/lib64/php{{ php_version }}/modules"
-php_xhprof_module_path: "/usr/lib64/php{{ php_version }}/modules"
+__php_tideways_module_path: "/usr/lib64/php{{ php_version }}/modules"
+__php_uploadprogress_module_path: "/usr/lib64/php{{ php_version }}/modules"
+__php_xdebug_module_path: "/usr/lib64/php{{ php_version }}/modules"
+__php_xhprof_module_path: "/usr/lib64/php{{ php_version }}/modules"