diff --git a/layouts/chromes/html5.php b/layouts/chromes/html5.php
index 7e370844d18a7..8979e47b6e9d9 100644
--- a/layouts/chromes/html5.php
+++ b/layouts/chromes/html5.php
@@ -23,7 +23,7 @@
 
 $moduleTag              = htmlspecialchars($params->get('module_tag', 'div'), ENT_QUOTES, 'UTF-8');
 $moduleAttribs          = [];
-$moduleAttribs['class'] = 'moduletable ' . htmlspecialchars($params->get('moduleclass_sfx'), ENT_QUOTES, 'UTF-8');
+$moduleAttribs['class'] = 'moduletable ' . htmlspecialchars($params->get('moduleclass_sfx', ''), ENT_QUOTES, 'UTF-8');
 $bootstrapSize          = (int) $params->get('bootstrap_size', 0);
 $moduleAttribs['class'] .= $bootstrapSize !== 0 ? ' col-md-' . $bootstrapSize : '';
 $headerTag              = htmlspecialchars($params->get('header_tag', 'h3'), ENT_QUOTES, 'UTF-8');