diff --git a/module/VuFind/src/VuFind/Auth/CAS.php b/module/VuFind/src/VuFind/Auth/CAS.php
index a3df80173d448ed752addb11097e62e1677f9d5e..18f5ddb1a83b556755b80cb5760700a01a1ac9dc 100644
--- a/module/VuFind/src/VuFind/Auth/CAS.php
+++ b/module/VuFind/src/VuFind/Auth/CAS.php
@@ -196,7 +196,7 @@ class CAS extends AbstractBase
             && isset($config->CAS->logout)
         ) {
             $casauth = $this->setupCAS();
-            if ($casauth->checkAuthentication() !== true) {
+            if ($casauth->checkAuthentication() === false) {
                 return true;
             }
         }