diff --git a/scripts/upgrade b/scripts/upgrade
index 83c7dd4..96b35a3 100644
--- a/scripts/upgrade
+++ b/scripts/upgrade
@@ -241,6 +241,16 @@ if grep -q "^matrix-$app" /etc/passwd; then
     adduser $app ssl-cert
 fi
 
+#=================================================
+# MIGRATION 13 : set PHP version if unset
+#=================================================
+
+# If phpversion doesn't exist, create it
+if [ -z "${phpversion:-}" ]; then
+	phpversion=8.3
+	ynh_app_setting_set --app=$app --key=phpversion --value=$phpversion
+fi
+
 #=================================================
 # DOWNLOAD, CHECK AND UNPACK SOURCE
 #=================================================