diff --git a/lib/SimpleSAML/SessionHandlerPHP.php b/lib/SimpleSAML/SessionHandlerPHP.php
index dbcd10062d2a55177dd99ed8bfc2f309d24f1bd4..3686356ac04aad906f5b2edf36e2414a157550b2 100644
--- a/lib/SimpleSAML/SessionHandlerPHP.php
+++ b/lib/SimpleSAML/SessionHandlerPHP.php
@@ -183,7 +183,7 @@ class SessionHandlerPHP extends SessionHandler
      */
     public function getCookieSessionId()
     {
-        if (!self::hasSessionCookie()) {
+        if (!$this->hasSessionCookie()) {
             return null; // there's no session cookie, can't return ID
         }