diff --git a/Render/Html/GetNelmioAsset.php b/Render/Html/GetNelmioAsset.php
index be64283..0ec88f9 100644
--- a/Render/Html/GetNelmioAsset.php
+++ b/Render/Html/GetNelmioAsset.php
@@ -31,7 +31,7 @@ class GetNelmioAsset extends AbstractExtension
         $this->resourcesDir = __DIR__.'/../../Resources/public';
     }
 
-    public function getFunctions()
+    public function getFunctions(): array
     {
         return [
             new TwigFunction('nelmioAsset', $this, ['is_safe' => ['html']]),