diff --git a/Classes/ViewHelpers/SkillGroupingViewHelper.php b/Classes/ViewHelpers/SkillGroupingViewHelper.php
index 2a2fdf4..9720c34 100644
--- a/Classes/ViewHelpers/SkillGroupingViewHelper.php
+++ b/Classes/ViewHelpers/SkillGroupingViewHelper.php
@@ -44,7 +44,7 @@ class SkillGroupingViewHelper extends AbstractViewHelper
 
     protected $escapeOutput = false;
 
-    public function initializeArguments()
+    public function initializeArguments(): void
     {
         $this->registerArgument('skills', 'array', 'An array of skills to group', false, []);
         $this->registerArgument('skillSet', SkillSet::class, 'The skills of this skill set will be grouped');
diff --git a/Classes/ViewHelpers/VerificationViewHelper.php b/Classes/ViewHelpers/VerificationViewHelper.php
index 46f1778..6878855 100644
--- a/Classes/ViewHelpers/VerificationViewHelper.php
+++ b/Classes/ViewHelpers/VerificationViewHelper.php
@@ -36,7 +36,7 @@ abstract class VerificationViewHelper extends AbstractViewHelper
 
     protected $escapeOutput = false;
 
-    public function initializeArguments()
+    public function initializeArguments(): void
     {
         $this->registerArgument('skill', 'integer', 'ID of the Skill.');
         $this->registerArgument('skillSet', 'integer', 'ID of the SkillSet.');