diff --git a/lib/minimizer/css.php b/lib/minimizer/css.php
index 0f1435fde4522a89114421e6be111ae5f8ca1f5f..41886087199f3e9e44989db6fb31290ce8b9be8a 100644
--- a/lib/minimizer/css.php
+++ b/lib/minimizer/css.php
@@ -16,7 +16,7 @@ class OC_Minimizer_CSS extends OC_Minimizer
 
 			$in_root = false;
 			foreach(OC::$APPSROOTS as $app_root) {
-				if(strpos($file, $app_root['path']) === 0) {
+				if(strpos($file, $app_root['path'].'/') === 0) {
 					$in_root = rtrim($webroot.$app_root['url'], '/');
 					break;
 				}