diff --git a/htdocs/comm/action/index.php b/htdocs/comm/action/index.php
index aa457470cc5..71c45be9eff 100644
--- a/htdocs/comm/action/index.php
+++ b/htdocs/comm/action/index.php
@@ -363,17 +363,16 @@ if (! empty($conf->use_javascript_ajax))
 	{
 		foreach ($showextcals as $val)
 		{
-			$htmlname = dol_string_nospecial($val['name']);
-			$htmlname = dol_string_nospecial($htmlname,'_',array("\.","#"));
+			$htmlname = md5($val['name']);
 			$s.='<script type="text/javascript">' . "\n";
 			$s.='jQuery(document).ready(function () {' . "\n";
-			$s.='		jQuery("#check_' . $htmlname . '").click(function() {';
+			$s.='		jQuery("#check_ext' . $htmlname . '").click(function() {';
 			$s.=' 		/* alert("'.$htmlname.'"); */';
-			$s.=' 		jQuery(".family_' . $htmlname . '").toggle();';
+			$s.=' 		jQuery(".family_ext' . $htmlname . '").toggle();';
 			$s.='		});' . "\n";
 			$s.='});' . "\n";
 			$s.='</script>' . "\n";
-			$s.='<div class="nowrap float"><input type="checkbox" id="check_' . $htmlname . '" name="check_' . $htmlname . '" checked="true"> ' . $val ['name'] . ' &nbsp; </div>';
+			$s.='<div class="nowrap float"><input type="checkbox" id="check_ext' . $htmlname . '" name="check_ext' . $htmlname . '" checked="true"> ' . $val ['name'] . ' &nbsp; </div>';
 		}
 	}
 	$s.='<div class="nowrap float"><input type="checkbox" id="check_birthday" name="check_birthday"> '.$langs->trans("AgendaShowBirthdayEvents").' &nbsp; </div>';
diff --git a/htdocs/comm/action/peruser.php b/htdocs/comm/action/peruser.php
index 9d16ea0fc44..cb2aa9fa99f 100644
--- a/htdocs/comm/action/peruser.php
+++ b/htdocs/comm/action/peruser.php
@@ -305,16 +305,16 @@ if ($conf->use_javascript_ajax)
 		{
 			foreach ($showextcals as $val)
 			{
-				$htmlname = dol_string_nospecial($val['name']);
+				$htmlname = md5($val['name']);
 				$s.='<script type="text/javascript">' . "\n";
 				$s.='jQuery(document).ready(function () {' . "\n";
-				$s.='		jQuery("#check_' . $htmlname . '").click(function() {';
+				$s.='		jQuery("#check_ext' . $htmlname . '").click(function() {';
 				$s.=' 		/* alert("'.$htmlname.'"); */';
-				$s.=' 		jQuery(".family_' . $htmlname . '").toggle();';
+				$s.=' 		jQuery(".family_ext' . $htmlname . '").toggle();';
 				$s.='		});' . "\n";
 				$s.='});' . "\n";
 				$s.='</script>' . "\n";
-				$s.='<div class="nowrap float"><input type="checkbox" id="check_' . $htmlname . '" name="check_' . $htmlname . '" checked="true"> ' . $val ['name'] . ' &nbsp; </div>';
+				$s.='<div class="nowrap float"><input type="checkbox" id="check_ext' . $htmlname . '" name="check_ext' . $htmlname . '" checked="true"> ' . $val ['name'] . ' &nbsp; </div>';
 			}
 		}
 	}