diff --git a/scripts/_common.sh b/scripts/_common.sh
index 80e5275..52b12cb 100644
--- a/scripts/_common.sh
+++ b/scripts/_common.sh
@@ -3,10 +3,26 @@
 #=================================================
 # COMMON VARIABLES
 #=================================================
+# PHP APP SPECIFIC
+#=================================================
+# Depending on its version, YunoHost uses different default PHP version:
+## YunoHost version "11.X" => PHP 7.4
+## YunoHost version "4.X"  => PHP 7.3
+#
+# This behaviour can be overridden by setting the YNH_PHP_VERSION variable
+#YNH_PHP_VERSION=7.3
+#YNH_PHP_VERSION=7.4
+#YNH_PHP_VERSION=8.0
+YNH_PHP_VERSION=8.1
+# For more information, see the PHP application helper: https://github.com/YunoHost/yunohost/blob/dev/helpers/php#L3-L6
+# Or this app package depending on PHP: https://github.com/YunoHost-Apps/grav_ynh/blob/master/scripts/_common.sh
+# PHP dependencies used by the app (must be on a single line)
+php_dependencies="php${YNH_PHP_VERSION}-xml php${YNH_PHP_VERSION}-ldap php${YNH_PHP_VERSION}-gd"
+# or, if you do not need a custom YNH_PHP_VERSION:
+###php_dependencies="php$YNH_DEFAULT_PHP_VERSION-deb1 php$YNH_DEFAULT_PHP_VERSION-deb2"
 
-YNH_PHP_VERSION="7.3"
-
-pkg_dependencies="php${YNH_PHP_VERSION}-xml php${YNH_PHP_VERSION}-ldap php${YNH_PHP_VERSION}-gd"
+# dependencies used by the app (must be on a single line)
+pkg_dependencies="$php_dependencies"
 
 #=================================================
 # PERSONAL HELPERS