diff --git a/htdocs/core/class/html.form.class.php b/htdocs/core/class/html.form.class.php
index f55eb81cdcc..ce0d8babbc6 100644
--- a/htdocs/core/class/html.form.class.php
+++ b/htdocs/core/class/html.form.class.php
@@ -4110,7 +4110,7 @@ class Form
                 {
                     global $dolibarr_main_url_root;
                     $ret.='<!-- Put link to gravatar -->';
-                    $ret.='<img alt="Photo found on Gravatar" title="Photo Gravatar.com - email '.$email.'" border="0" width="'.$width.'" src="http://www.gravatar.com/avatar/'.dol_hash($email).'?s='.$width.'&d='.urlencode(dol_buildpath('/theme/common/nophoto.jpg',2)).'">';
+                    $ret.='<img alt="Photo found on Gravatar" title="Photo Gravatar.com - email '.$email.'" border="0" width="'.$width.'" src="https://www.gravatar.com/avatar/'.dol_hash($email).'?s='.$width.'&d='.urlencode(dol_buildpath('/theme/common/nophoto.jpg',2)).'">';
                 }
                 else
                 {