diff --git a/src/Webservice/WebService.php b/src/Webservice/WebService.php
index d8a9d36..2818b1c 100644
--- a/src/Webservice/WebService.php
+++ b/src/Webservice/WebService.php
@@ -16,6 +16,8 @@ abstract class WebService
 
     private $version = null;
 
+    private $sessionStarted = false;
+
     public function __construct($version) {
         $this->version = $version;
     }
@@ -71,8 +73,11 @@ abstract class WebService
 
     protected function startSession()
     {
-        session_save_path(Configuration::get('session.save_path'));
-        session_start();
+        if (!$this->sessionStarted) {
+            session_save_path(Configuration::get('session.save_path'));
+            session_start();
+            $this->sessionStarted = true;
+        }
     }
 
     /**