diff --git a/htdocs/core/modules/modFckeditor.class.php b/htdocs/core/modules/modFckeditor.class.php
index fa3a66c37cc..631dba395fe 100644
--- a/htdocs/core/modules/modFckeditor.class.php
+++ b/htdocs/core/modules/modFckeditor.class.php
@@ -63,7 +63,7 @@ class modFckeditor extends DolibarrModules
 		$this->config_page_url = array("fckeditor.php");
 
 		// Dependencies
-		$this->disabled = in_array(constant('JS_CKEDITOR'), array('disabled', 'disabled/'));
+		$this->disabled = (defined('JS_CKEDITOR') && in_array(constant('JS_CKEDITOR'), array('disabled', 'disabled/')));
 		$this->depends = array();
 		$this->requiredby = array('modWebsites');