diff --git a/main/inc/lib/online.inc.php b/main/inc/lib/online.inc.php
index 71aa807b31..1581c5c9a2 100755
--- a/main/inc/lib/online.inc.php
+++ b/main/inc/lib/online.inc.php
@@ -225,7 +225,7 @@ function online_logout($user_id = null, $logout_redirect = false)
         exit;
     }
 
-    if ($uinfo['auth_source'] !== PLATFORM_AUTH_SOURCE && api_is_cas_activated()) {
+    if ($uinfo['auth_source'] === CAS_AUTH_SOURCE && api_is_cas_activated()) {
         require_once __DIR__.'/../../auth/cas/cas_var.inc.php';
         if (phpCas::isInitialized()) {
             phpCAS::logout();