diff --git a/components/ILIAS/BookingManager/BookingService/class.ilBookingGatewayGUI.php b/components/ILIAS/BookingManager/BookingService/class.ilBookingGatewayGUI.php
index c6ad0f1f3255..ee95ae9ed325 100755
--- a/components/ILIAS/BookingManager/BookingService/class.ilBookingGatewayGUI.php
+++ b/components/ILIAS/BookingManager/BookingService/class.ilBookingGatewayGUI.php
@@ -174,7 +174,11 @@ public function executeCommand(): void
             case "ilbookingreservationsgui":
                 $this->showPoolSelector("ilbookingreservationsgui");
                 $this->setSubTabs("reservations");
-                $res_gui = new ilBookingReservationsGUI($this->pool, $this->help, $this->obj_id);
+                $res_gui = new ilBookingReservationsGUI(
+                    $this->pool,
+                    $this->help,
+                    ilObject::_lookupType($this->obj_id) !== 'crs' ? $this->obj_id : null
+                );
                 $this->ctrl->forwardCommand($res_gui);
                 break;
 
diff --git a/components/ILIAS/BookingManager/Reservations/class.ilBookingReservationsGUI.php b/components/ILIAS/BookingManager/Reservations/class.ilBookingReservationsGUI.php
index e994a4656545..fb0f466c2ed4 100755
--- a/components/ILIAS/BookingManager/Reservations/class.ilBookingReservationsGUI.php
+++ b/components/ILIAS/BookingManager/Reservations/class.ilBookingReservationsGUI.php
@@ -30,7 +30,7 @@ class ilBookingReservationsGUI
     protected array $raw_post_data;
     protected \ILIAS\BookingManager\StandardGUIRequest $book_request;
     protected ilBookingHelpAdapter $help;
-    protected int $context_obj_id;
+    protected ?int $context_obj_id;
     protected ilCtrl $ctrl;
     protected ilGlobalTemplateInterface $tpl;
     protected ilLanguage $lng;
@@ -43,11 +43,8 @@ class ilBookingReservationsGUI
     protected string $reservation_id;  // see BookingReservationDBRepo, obj_user_(slot)_context
     protected int $booked_user;
 
-    public function __construct(
-        ilObjBookingPool $pool,
-        ilBookingHelpAdapter $help,
-        int $context_obj_id = 0
-    ) {
+    public function __construct(ilObjBookingPool $pool, ilBookingHelpAdapter $help, ?int $context_obj_id = null)
+    {
         global $DIC;
 
         $this->tpl = $DIC->ui()->mainTemplate();
@@ -161,7 +158,7 @@ protected function getReservationsTable(?string $reservation_id = null): ilBooki
             $show_all,
             $filter,
             $reservation_id,
-            $this->context_obj_id > 0 ? [$this->context_obj_id] : null
+            $this->context_obj_id !== null ? [$this->context_obj_id] : null
         );
     }