diff --git a/htdocs/core/class/html.form.class.php b/htdocs/core/class/html.form.class.php
index 5813c45047a..7f7f3313139 100644
--- a/htdocs/core/class/html.form.class.php
+++ b/htdocs/core/class/html.form.class.php
@@ -5018,7 +5018,7 @@ class Form
 			}
 			$formconfirm .= '<br>';
 
-			if (empty($conf->use_javascript_ajax)) {
+			if (!empty($conf->use_javascript_ajax)) {
 				$formconfirm .= '<!-- code to disable button to avoid double clic -->';
 				$formconfirm .= '<script type="text/javascript">'."\n";
 				$formconfirm .= '