diff --git a/Classes/ViewHelpers/Format/ReplaceViewHelper.php b/Classes/ViewHelpers/Format/ReplaceViewHelper.php
index e1a3c8485..483d17d6e 100644
--- a/Classes/ViewHelpers/Format/ReplaceViewHelper.php
+++ b/Classes/ViewHelpers/Format/ReplaceViewHelper.php
@@ -41,7 +41,7 @@ public static function renderStatic(
         \Closure $renderChildrenClosure,
         RenderingContextInterface $renderingContext
     ) {
-        $content = $renderChildrenClosure();
+        $content = (string) $renderChildrenClosure();
         /** @var string $substring */
         $substring = (string) $arguments['substring'];
         /** @var string $replacement */