diff --git a/tools/html/taglib/HtmlIteratorTag.php b/tools/html/taglib/HtmlIteratorTag.php
index 519f2132b..a1d2fe047 100644
--- a/tools/html/taglib/HtmlIteratorTag.php
+++ b/tools/html/taglib/HtmlIteratorTag.php
@@ -316,7 +316,7 @@ public function transformIterator() {
          $fallbackObjectId = $this->getFallbackContentItemObjectId();
 
          if ($fallbackObjectId !== null) {
-            $fallbackMode = $this->getAttribute('fallback-mode');
+            $fallbackMode = $this->getAttribute('fallback-mode', self::FALLBACK_MODE_NORMAL);
 
             if ($fallbackMode === self::FALLBACK_MODE_NORMAL) {
                // activate auto-transformation to display fallback content.