diff --git a/Admin/Routes/Web/Backend.php b/Admin/Routes/Web/Backend.php
index 9b56e10..969e00e 100644
--- a/Admin/Routes/Web/Backend.php
+++ b/Admin/Routes/Web/Backend.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 use Modules\Kanban\Controller\BackendController;
 use Modules\Kanban\Models\PermissionState;
diff --git a/Theme/Backend/Lang/Navigation.en.lang.php b/Theme/Backend/Lang/Navigation.en.lang.php
index 073e4d3..16b057c 100644
--- a/Theme/Backend/Lang/Navigation.en.lang.php
+++ b/Theme/Backend/Lang/Navigation.en.lang.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 /**
  * Orange Management
  *
diff --git a/Theme/Backend/Lang/en.lang.php b/Theme/Backend/Lang/en.lang.php
index d13cc5d..90b8045 100644
--- a/Theme/Backend/Lang/en.lang.php
+++ b/Theme/Backend/Lang/en.lang.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 /**
  * Orange Management
  *
diff --git a/Theme/Backend/kanban-board-create.tpl.php b/Theme/Backend/kanban-board-create.tpl.php
index b6388b8..82e9c95 100644
--- a/Theme/Backend/kanban-board-create.tpl.php
+++ b/Theme/Backend/kanban-board-create.tpl.php
@@ -1,2 +1,2 @@
-<?php
-echo $this->getData('nav')->render();
\ No newline at end of file
+<?php declare(strict_types=1);
+echo $this->getData('nav')->render();
diff --git a/Theme/Backend/kanban-board.tpl.php b/Theme/Backend/kanban-board.tpl.php
index 2d3b7a2..ec93c5d 100644
--- a/Theme/Backend/kanban-board.tpl.php
+++ b/Theme/Backend/kanban-board.tpl.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 $board = $this->getData('board');
 $columns = $board->getColumns();
 // todo: column width should be % but with min-width and on small screens full width
diff --git a/Theme/Backend/kanban-card.tpl.php b/Theme/Backend/kanban-card.tpl.php
index fa08b6b..6755661 100644
--- a/Theme/Backend/kanban-card.tpl.php
+++ b/Theme/Backend/kanban-card.tpl.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 $card = $this->getData('card');
 $comments = $card->getComments();
 ?>
diff --git a/Theme/Backend/kanban-dashboard.tpl.php b/Theme/Backend/kanban-dashboard.tpl.php
index 1aa9b2d..2ee3774 100644
--- a/Theme/Backend/kanban-dashboard.tpl.php
+++ b/Theme/Backend/kanban-dashboard.tpl.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 $boards = $this->getData('boards');
 
 echo $this->getData('nav')->render(); ?>