diff --git a/setup/compiler.class.inc.php b/setup/compiler.class.inc.php
index 33d3986c2..5d1ac171d 100644
--- a/setup/compiler.class.inc.php
+++ b/setup/compiler.class.inc.php
@@ -27,7 +27,6 @@ class DOMFormatException extends Exception
 class MFCompiler
 {
 	protected $oFactory;
-	protected $aSourceDirs;
 
 	protected $aRootClasses;
 	protected $aLog;
diff --git a/setup/modelfactory.class.inc.php b/setup/modelfactory.class.inc.php
index e3e1cf026..ec7db8ef2 100644
--- a/setup/modelfactory.class.inc.php
+++ b/setup/modelfactory.class.inc.php
@@ -106,7 +106,7 @@ class MFModule
  */
 class ModelFactory
 {
-	protected $sRootDir;
+	protected $aRootDirs;
 	protected $oDOMDocument;
 	protected $oRoot;
 	protected $oModules;
@@ -119,9 +119,9 @@ class ModelFactory
 	static protected $aLoadErrors;
 
 	
-	public function __construct($sRootDir, $aRootNodeExtensions = array())
+	public function __construct($aRootDirs, $aRootNodeExtensions = array())
 	{
-		$this->sRootDir = $sRootDir;
+		$this->aRootDirs = $aRootDirs;
 		$this->oDOMDocument = new MFDocument();
 		$this->oRoot = $this->oDOMDocument->CreateElement('itop_design');
 		$this->oRoot->setAttribute('xmlns:xsi', "http://www.w3.org/2001/XMLSchema-instance");
@@ -1070,13 +1070,13 @@ EOF
 	}
 	
 	/**
-	 * Searches on disk in the root directory for module description files
+	 * Searches on disk in the root directories for module description files
 	 * and returns an array of MFModules
 	 * @return array Array of MFModules
 	 */
-	public function FindModules($sSubDirectory = '')
+	public function FindModules()
 	{
-		$aAvailableModules = ModuleDiscovery::GetAvailableModules($this->sRootDir, array($sSubDirectory));
+		$aAvailableModules = ModuleDiscovery::GetAvailableModules($this->aRootDirs);
 		$aResult = array();
 		foreach($aAvailableModules as $sId => $aModule)
 		{
diff --git a/setup/runtimeenv.class.inc.php b/setup/runtimeenv.class.inc.php
index 54142266d..287113edf 100644
--- a/setup/runtimeenv.class.inc.php
+++ b/setup/runtimeenv.class.inc.php
@@ -279,20 +279,25 @@ class RunTimeEnvironment
 		$sSourceDirFull = APPROOT.$sSourceDir;
 		if (!is_dir($sSourceDirFull))
 		{
-			throw new Exception("The source directory '$sSourceDir' does not exist (or could not be read)");
+			throw new Exception("The source directory '$sSourceDirFull' does not exist (or could not be read)");
 		}
-
+		$aDirsToCompile = array($sSourceDirFull);
+		if (is_dir(APPROOT.'extensions'))
+		{
+			$aDirsToCompile[] = APPROOT.'extensions';
+		}
+		
 		$aRet = array();
 
 		// Determine the installed modules
 		//
 		$oSourceConfig = new Config(APPCONF.$sSourceEnv.'/'.ITOP_CONFIG_FILE);
 		$oSourceEnv = new RunTimeEnvironment($sSourceEnv);
-		$aAvailableModules = $oSourceEnv->AnalyzeInstallation($oSourceConfig, $sSourceDir); //TODO: use an absolute PATH
+		$aAvailableModules = $oSourceEnv->AnalyzeInstallation($oSourceConfig, $aDirsToCompile);
 
 		// Do load the required modules
 		//
-		$oFactory = new ModelFactory($sSourceDirFull);
+		$oFactory = new ModelFactory($aDirsToCompile);
 		$aModules = $oFactory->FindModules();
 		foreach($aModules as $foo => $oModule)
 		{
@@ -308,13 +313,11 @@ class RunTimeEnvironment
 		return $aRet;
 	}
 
-	public function CompileFrom($sSourceEnv, $sSourceDir = null)
+	public function CompileFrom($sSourceEnv)
 	{
-		if (is_null($sSourceDir))
-		{
-			$oSourceConfig = new Config(utils::GetConfigFilePath($sSourceEnv));
-			$sSourceDir = $oSourceConfig->Get('source_dir');
-		}
+		$oSourceConfig = new Config(utils::GetConfigFilePath($sSourceEnv));
+		$sSourceDir = $oSourceConfig->Get('source_dir');
+
 		$sSourceDirFull = APPROOT.$sSourceDir;
 		// Do load the required modules
 		//
@@ -347,9 +350,10 @@ class RunTimeEnvironment
 
 			$sTargetDir = APPROOT.'env-'.$this->sTargetEnv;
 			self::MakeDirSafe($sTargetDir);
-			$oMFCompiler = new MFCompiler($oFactory, $sSourceDirFull);
+			$oMFCompiler = new MFCompiler($oFactory);
 			$oMFCompiler->Compile($sTargetDir);
-
+			
+			require_once(APPROOT.'/core/dict.class.inc.php');
 			MetaModel::ResetCache($this->sTargetEnv);
 		}
 	}
@@ -546,9 +550,12 @@ class RunTimeEnvironment
 	{
 		if (!is_dir($sDir))
 		{
-			@mkdir($sDir);
+			if (!@mkdir($sDir))
+			{
+				throw new Exception("Failed to create directory '$sTargetPath', please check the rights of the web server");
+			}
+			@chmod($sDir, 0770); // RWX for owner and group, nothing for others
 		}
-		@chmod($sDir, 0770); // RWX for owner and group, nothing for others
 	}
 
 	/**