diff --git a/src/BeSimple/SoapClient/WsdlDownloader.php b/src/BeSimple/SoapClient/WsdlDownloader.php
index 79e8423..9f62fe4 100644
--- a/src/BeSimple/SoapClient/WsdlDownloader.php
+++ b/src/BeSimple/SoapClient/WsdlDownloader.php
@@ -189,12 +189,12 @@ class WsdlDownloader
         $nodes = $xpath->query($query);
         if ($nodes->length > 0) {
             foreach ($nodes as $node) {
-                if ( $node->hasAttribute('schemaLocation') ) {
+                if ($node->hasAttribute('schemaLocation')) {
                     $schemaLocation = $node->getAttribute('schemaLocation');
                     if ($this->isRemoteFile($schemaLocation)) {
                         $schemaLocation = $this->download($schemaLocation);
                         $node->setAttribute('schemaLocation', $schemaLocation);
-                    } elseif (!is_null($parentFile)) {
+                    } elseif (null !== $parentFile) {
                         $schemaLocation = $this->resolveRelativePathInUrl($parentFile, $schemaLocation);
                         $schemaLocation = $this->download($schemaLocation);
                         $node->setAttribute('schemaLocation', $schemaLocation);