diff --git a/lib/base.php b/lib/base.php
index ddf410c3163417174deb54efdb61191462b0ec0f..52a497e076d0bef8d8d2eab356e837f9ffafb2e0 100644
--- a/lib/base.php
+++ b/lib/base.php
@@ -289,12 +289,12 @@ class OC{
 				$appswebroot = (string) OC::$APPSWEBROOT;
 				$webroot = (string) OC::$WEBROOT;
 				$filepath = OC::$APPSROOT . '/apps/' . OC::$REQUESTEDAPP . '/' . OC::$REQUESTEDFILE;
-				$cssfile = file_get_contents($filepath);
-				$cssfile = str_replace('%appswebroot%', $appswebroot, $cssfile);
-				$cssfile = str_replace('%webroot%', $webroot, $cssfile);
 				header('Content-Type: text/css');
 				OC_Response::enableCaching();
 				OC_Response::setLastModifiedHeader(filemtime($filepath));
+				$cssfile = file_get_contents($filepath);
+				$cssfile = str_replace('%appswebroot%', $appswebroot, $cssfile);
+				$cssfile = str_replace('%webroot%', $webroot, $cssfile);
 				OC_Response::setETagHeader(md5($cssfile));
 				header('Content-Length: '.strlen($cssfile));
 				echo $cssfile;