diff --git a/Twig/DataGridExtension.php b/Twig/DataGridExtension.php
index 6bacd5c0..59882932 100644
--- a/Twig/DataGridExtension.php
+++ b/Twig/DataGridExtension.php
@@ -110,7 +110,7 @@ public function getGlobals(): array
      *
      * @return array An array of functions
      */
-    public function getFunctions()
+    public function getFunctions(): array
     {
         return [
             new TwigFunction('grid', [$this, 'getGrid'], [