diff --git a/libraries/src/Document/HtmlDocument.php b/libraries/src/Document/HtmlDocument.php
index f4bf65ae23dd7..ee4c33e9267c3 100644
--- a/libraries/src/Document/HtmlDocument.php
+++ b/libraries/src/Document/HtmlDocument.php
@@ -542,7 +542,7 @@ public function getBuffer($type = null, $name = null, $attribs = array())
                     ]
                 )
             );
-            $cbuffer = $cache->get('cbuffer_' . $type);
+            $cbuffer = $cache->get('cbuffer_' . $type) ?: [];
 
             if (isset($cbuffer[$hash])) {
                 return Cache::getWorkarounds($cbuffer[$hash], array('mergehead' => 1));