diff --git a/library/SSRS/Soap/NTLM.php b/library/SSRS/Soap/NTLM.php
index 33b4fd6..5922f46 100755
--- a/library/SSRS/Soap/NTLM.php
+++ b/library/SSRS/Soap/NTLM.php
@@ -17,8 +17,11 @@ class NTLM extends \SoapClient {
 
     function __construct($wsdl, $options = array()) {
         if (empty($options['cache_wsdl_path'])) {
-            $options['cache_wsdl_path'] = '/tmp/' . md5($wsdl) . '.wsdl';
+            $options['cache_wsdl_path'] = sys_get_temp_dir();
         }
+        if(!preg_match('/'.preg_quote(DIRECTORY_SEPARATOR, '/').'$/', $options['cache_wsdl_path']))
+            $options['cache_wsdl_path'] .= DIRECTORY_SEPARATOR;
+        $options['cache_wsdl_path'] .= md5($wsdl) . '.wsdl';
 
         if (array_key_exists('username', $options)) {
             $this->setUsername($options['username']);
@@ -79,16 +82,20 @@ public function setPassword($password) {
 
     public function setCachePath($file) {
         $folder = dirname($file);
+        $testFilePath = $folder.DIRECTORY_SEPARATOR.uniqid('test-cache-');
 
         if (file_exists($file) && false === is_writable($file)) {
             throw new RuntimeException("WSDL cache file not writeable");
         } elseif (false === is_dir($folder)) {
             throw new RuntimeException("WSDL cache parent folder does not exist");
-        } elseif (false === is_writeable($folder)) {
+        } elseif (touch($testFilePath) === false) {
             throw new RuntimeException("WSDL cache parent folder not writeable");
+        } else {
+            @unlink($testFilePath);
         }
 
         $this->_cachePath = $file;
+
         return $this;
     }