diff --git a/install_minimal/upgrades/airtime-1.9.0/airtime-upgrade.php b/install_minimal/upgrades/airtime-1.9.0/airtime-upgrade.php
index 8243ea31b..86b973570 100644
--- a/install_minimal/upgrades/airtime-1.9.0/airtime-upgrade.php
+++ b/install_minimal/upgrades/airtime-1.9.0/airtime-upgrade.php
@@ -547,7 +547,8 @@ class Airtime190Upgrade{
 
     public static function InstallAirtimePhpServerCode($phpDir)
     {
-
+        // delete old files
+        exec("rm -rf ".$phpDir);
         $AIRTIME_SRC = realpath(__DIR__.'/../../../airtime_mvc');
 
         echo "* Installing PHP code to ".$phpDir.PHP_EOL;