diff --git a/lib/private/Installer.php b/lib/private/Installer.php
index 6aaa6fe6ac..67c949bc13 100644
--- a/lib/private/Installer.php
+++ b/lib/private/Installer.php
@@ -91,7 +91,12 @@ class Installer {
 	 * @return integer
 	 */
 	public function installApp($appId) {
-		$basedir = OC_App::getInstallPath().'/'.$appId;
+		$app = \OC_App::findAppInDirectories($appId);
+		if($app === false) {
+			throw new \Exception('App not found in any app directory');
+		}
+
+		$basedir = $app['path'].'/'.$appId;
 		$info = OC_App::getAppInfo($basedir.'/appinfo/info.xml', true);
 
 		//install the database
diff --git a/lib/private/legacy/app.php b/lib/private/legacy/app.php
index 6b5c4f3978..a89a4650c5 100644
--- a/lib/private/legacy/app.php
+++ b/lib/private/legacy/app.php
@@ -555,7 +555,7 @@ class OC_App {
 	 * @param string $appId
 	 * @return false|string
 	 */
-	protected static function findAppInDirectories($appId) {
+	public static function findAppInDirectories($appId) {
 		$sanitizedAppId = self::cleanAppId($appId);
 		if($sanitizedAppId !== $appId) {
 			return false;