diff --git a/src/ExtensionInstaller.php b/src/ExtensionInstaller.php
index 12bdead..166ee98 100644
--- a/src/ExtensionInstaller.php
+++ b/src/ExtensionInstaller.php
@@ -70,7 +70,7 @@ public function install(InstalledRepositoryInterface $repo, PackageInterface $pa
         $postInstall = function () use ($package) {
             $config_file = $this->rcubeConfigFile();
             $package_name = $this->getPackageName($package);
-            $package_dir = $this->getVendorDir() . \DIRECTORY_SEPARATOR . $package_name;
+            $package_dir = $this->getInstallPath($package);
             $extra = $package->getExtra();
 
             if (is_writable($config_file) && \PHP_SAPI === 'cli' && $this->confirmInstall($package_name)) {
@@ -143,8 +143,7 @@ public function update(InstalledRepositoryInterface $repo, PackageInterface $ini
         $fs = new Filesystem();
 
         // backup persistent files e.g. config.inc.php
-        $package_name = $this->getPackageName($initial);
-        $package_dir = $this->getVendorDir() . \DIRECTORY_SEPARATOR . $package_name;
+        $package_dir = $this->getInstallPath($initial);
         $temp_dir = $package_dir . '-' . sprintf('%010d%010d', mt_rand(), mt_rand());
 
         // make a backup of existing files (for restoring persistent files)
@@ -152,7 +151,7 @@ public function update(InstalledRepositoryInterface $repo, PackageInterface $ini
 
         $postUpdate = function () use ($target, $extra, $fs, $temp_dir) {
             $package_name = $this->getPackageName($target);
-            $package_dir = $this->getVendorDir() . \DIRECTORY_SEPARATOR . $package_name;
+            $package_dir = $this->getInstallPath($target);
 
             // restore persistent files
             $persistent_files = !empty($extra['roundcube']['persistent-files']) ? $extra['roundcube']['persistent-files'] : ['config.inc.php'];
@@ -217,7 +216,7 @@ public function uninstall(InstalledRepositoryInterface $repo, PackageInterface $
         $postUninstall = function () use ($package, $config) {
             // post-uninstall: deactivate package
             $package_name = $this->getPackageName($package);
-            $package_dir = $this->getVendorDir() . \DIRECTORY_SEPARATOR . $package_name;
+            $package_dir = $this->getInstallPath($package);
 
             $this->rcubeAlterConfig($package_name, false);
 
@@ -400,7 +399,7 @@ private function rcubeRunScript($script, PackageInterface $package)
     {
         $package_name = $this->getPackageName($package);
         $package_type = $package->getType();
-        $package_dir = $this->getVendorDir() . \DIRECTORY_SEPARATOR . $package_name;
+        $package_dir = $this->getInstallPath($package);
 
         // check for executable shell script
         if (($scriptfile = realpath($package_dir . \DIRECTORY_SEPARATOR . $script)) && is_executable($scriptfile)) {
@@ -424,7 +423,7 @@ private function rcubeRunScript($script, PackageInterface $package)
     }
 
     /**
-     * normalize Roundcube version string.
+     * Normalize Roundcube version string.
      */
     private static function versionNormalize(string $version): string
     {