Index: core/install.php
===================================================================
--- core/install.php
+++ core/install.php
@@ -883,7 +883,7 @@
 					$user_helper->loginUser('root', $this->Application->GetVar('root_password'));
 
 					// import base language for core (english)
-					$this->toolkit->ImportLanguage('/core/install/english');
+					$this->toolkit->ImportLanguage('/core/install/english', false);
 
 					// make sure imported language is set as active in session, created during installation
 					$this->Application->Session->SetField('Language', 1);
@@ -1007,7 +1007,7 @@
 							preg_match_all('/' . VERSION_MARK . '/s', $sqls, $regs);
 
 							// import module language pack
-							$this->toolkit->ImportLanguage('/' . $module_info['Path'] . 'install/english', true);
+							$this->toolkit->ImportLanguage('/' . $module_info['Path'] . 'install/english');
 
 							// perform advanced language pack upgrade
 							foreach ($regs[1] as $version) {
Index: core/install/install_toolkit.php
===================================================================
--- core/install/install_toolkit.php
+++ core/install/install_toolkit.php
@@ -428,7 +428,7 @@
 		 * @param bool $upgrade
 		 * @todo Import for "core/install/english.lang" (322KB) takes 18 seconds to work on Windows
 		 */
-		function ImportLanguage($lang_file, $upgrade = false)
+		public function ImportLanguage($lang_file, $upgrade = true)
 		{
 			$lang_file = FULL_PATH.$lang_file.'.lang';
 			if (!file_exists($lang_file)) {