diff --git a/install/lib/installer_base.lib.php b/install/lib/installer_base.lib.php
index 956782543b81d18f48dfb45946e696475a0a7ea6..3a0f87af1e6967968197e15c29d115e6a389ed24 100644
--- a/install/lib/installer_base.lib.php
+++ b/install/lib/installer_base.lib.php
@@ -2637,7 +2637,7 @@ class installer_base {
 			$content = rfsel($conf['ispconfig_install_dir'].'/server/conf-custom/install/nginx_apps.vhost.master', 'tpl/nginx_apps.vhost.master');
 
 			// Enable SSL if a cert is in place.
-			if(is_file($conf['ispconfig_install_dir'].'/interface/ssl/ispserver.crt') && is_file($install_dir.'/interface/ssl/ispserver.key')) {
+			if(is_file($conf['ispconfig_install_dir'].'/interface/ssl/ispserver.crt') && is_file($conf['ispconfig_install_dir'].'/interface/ssl/ispserver.key')) {
 				$content = str_replace('{ssl_on}', 'ssl', $content);
 				$content = str_replace('{ssl_comment}', '', $content);
 			} else {