diff --git a/library/Notifications/Web/FilterRenderer.php b/library/Notifications/Web/FilterRenderer.php
index 7ea4865a..b3432033 100644
--- a/library/Notifications/Web/FilterRenderer.php
+++ b/library/Notifications/Web/FilterRenderer.php
@@ -9,7 +9,7 @@
 
 class FilterRenderer extends Renderer
 {
-    protected function renderCondition(Filter\Condition $condition)
+    protected function renderCondition(Filter\Condition $condition): void
     {
         $value = $condition->getValue();
         if (is_bool($value) && ! $value) {