diff --git a/app/controllers/resources/messages.php b/app/controllers/resources/messages.php
index ae202e58c6070ffcf199bc42a9b6b0506c2cf07c..da3ca87f7aa2ce1abff36be383d7dbd0a51425f7 100644
--- a/app/controllers/resources/messages.php
+++ b/app/controllers/resources/messages.php
@@ -68,7 +68,7 @@ class Resources_MessagesController extends AuthenticatedController
             $this->room_selection = Request::get('room_selection');
             $this->room_ids = Request::getArray('room_ids');
             $this->selected_rooms = Room::findMany($this->room_ids);
-            $this->clipboard_id = Request::get('clipboard_id');
+            $this->clipboard_id = Request::int('clipboard_id');
 
             //First validation:
 
diff --git a/app/controllers/resources/print.php b/app/controllers/resources/print.php
index 8674fae63bf4a584901c2d795f87d7e9a081147f..811893564b4d99f64bba59ab41dc26e72abb05c2 100644
--- a/app/controllers/resources/print.php
+++ b/app/controllers/resources/print.php
@@ -132,7 +132,7 @@ class Resources_PrintController extends AuthenticatedController
         //clipboard, the selected date and the selected schedule type.
         //Furthermore a date and the type of schedule has been selected.
         // Also check for booking types to export.
-        $this->selected_clipboard_id = Request::get('clipboard_id');
+        $this->selected_clipboard_id = Request::int('clipboard_id');
         $this->schedule_type = Request::get('schedule_type');
         $this->selected_date_string = Request::get('date');
         $this->selected_booking_types = Request::intArray('bookingtypes') ?:
diff --git a/app/controllers/resources/room_request.php b/app/controllers/resources/room_request.php
index 8cc87023e4d7a89618700179869da5d24d8d8499..247de5c0f9783f9bfa95620c8549a50eb23c82ed 100644
--- a/app/controllers/resources/room_request.php
+++ b/app/controllers/resources/room_request.php
@@ -1302,7 +1302,7 @@ class Resources_RoomRequestController extends AuthenticatedController
 
         $this->clipboards = Clipboard::getClipboardsForUser($this->current_user->id, ['Room']);
 
-        $this->selected_clipboard_id = Request::get('selected_clipboard_id');
+        $this->selected_clipboard_id = Request::int('selected_clipboard_id');
         if (!$this->selected_clipboard_id) {
             if (count($this->clipboards) > 0) {
                 $this->selected_clipboard_id = $this->clipboards[0]->id;
diff --git a/app/controllers/room_management/planning.php b/app/controllers/room_management/planning.php
index a63e4ab19f0378cb693daac7e6c01b434f3e7bda..70fd566920d5e29f31246de4ceff6ac2be9f0940 100644
--- a/app/controllers/room_management/planning.php
+++ b/app/controllers/room_management/planning.php
@@ -30,7 +30,7 @@ class RoomManagement_PlanningController extends AuthenticatedController
         if (Navigation::hasItem('/resources/planning/index')) {
             Navigation::activateItem('/resources/planning/index');
         }
-        $selected_clipboard_id = Request::get('clipboard_id', $selected_clipboard_id);
+        $selected_clipboard_id = Request::int('clipboard_id', $selected_clipboard_id);
 
         $this->no_clipboard = false;
         $this->no_rooms = false;
@@ -271,7 +271,7 @@ class RoomManagement_PlanningController extends AuthenticatedController
             Navigation::activateItem('/resources/planning/semestergroup_plan');
         }
 
-        $selected_clipboard_id = Request::get('clipboard_id', $selected_clipboard_id);
+        $selected_clipboard_id = Request::int('clipboard_id', $selected_clipboard_id);
 
         $this->no_clipboard = false;
         $this->no_rooms = false;
@@ -1066,7 +1066,7 @@ class RoomManagement_PlanningController extends AuthenticatedController
             Navigation::activateItem('/resources/planning/booking_comments');
         }
 
-        $selected_clipboard_id = Request::get('clipboard_id', $selected_clipboard_id);
+        $selected_clipboard_id = Request::int('clipboard_id', $selected_clipboard_id);
         $this->standalone = false;
 
         if ($selected_clipboard_id) {
diff --git a/lib/classes/sidebar/ClipboardWidget.php b/lib/classes/sidebar/ClipboardWidget.php
index abc0d6ca16a850611835829f05a94a501803f78f..1209c952c88082e6b3931fac12fc3a7b79a40151 100644
--- a/lib/classes/sidebar/ClipboardWidget.php
+++ b/lib/classes/sidebar/ClipboardWidget.php
@@ -84,7 +84,7 @@ class ClipboardWidget extends SidebarWidget
         if (Request::submitted('clipboard_update_session_special_action')) {
             CSRFProtection::verifyUnsafeRequest();
 
-            $_SESSION['selected_clipboard_id'] = Request::get('selected_clipboard_id');
+            $_SESSION['selected_clipboard_id'] = Request::int('selected_clipboard_id');
         }
     }