diff --git a/class/class.core.php b/class/class.core.php
index ac9780e..7969d55 100644
--- a/class/class.core.php
+++ b/class/class.core.php
@@ -1463,8 +1463,8 @@
 				if (defined('RUB_ID'))
 				{
 					$replace = [
-						'[tag:rubheader]' => $this->curentdoc->rubric_header_template,
-						'[tag:rubfooter]' => $this->curentdoc->rubric_footer_template
+						'[tag:rubheader]' => $this->curentdoc->rubric_header_template ?? '',
+						'[tag:rubfooter]' => $this->curentdoc->rubric_footer_template ?? ''
 					];
 
 					$out = str_replace(array_keys($replace), array_values($replace), $out);