diff --git a/Assetic/Filter/CssURLRewriteFilter.php b/Assetic/Filter/CssURLRewriteFilter.php
index 0a1eb76..7ea6f74 100644
--- a/Assetic/Filter/CssURLRewriteFilter.php
+++ b/Assetic/Filter/CssURLRewriteFilter.php
@@ -90,7 +90,7 @@ private function getSubstringAfterNString($string, $searchString, $afterN)
     {
         $i=0;
         $pos = -1;
-        while (($pos=strpos($string, $searchString, $pos+1)) !== false) {
+        while (($pos = strpos($string, $searchString, $pos + 1)) !== false) {
             $i++;
 
             if ($i==$afterN) {
@@ -104,10 +104,10 @@ private function getSubstringAfterNString($string, $searchString, $afterN)
     private function calculateSwitchPath()
     {
         $targetPath = dirname($this->asset->getTargetPath());
-        $numDirs = substr_count($targetPath, '/')+1;
+        $numDirs = substr_count($targetPath, '/') + 1;
 
         $output = '';
-        for ($i=0; $i<$numDirs; $i++) {
+        for ($i=0; $i < $numDirs; $i++) {
             $output .= '../';
         }
 
@@ -121,7 +121,7 @@ private function calculateSwitchPath()
                     $request = $this->kernel->getContainer()->get('request');
                 }
                 
-                if (substr($request->getBaseUrl(), -4) != '.php') {
+                if ($request && substr($request->getBaseUrl(), -4) != '.php') {
                     $output = substr($output, 3);
                 }
             } catch (InactiveScopeException $e) {