--- /usr/share/univention-management-console-frontend/js/umc/modules/schoolusers.js.orig      2019-05-16 10:43:00.891234637 +0200
+++ /usr/share/univention-management-console-frontend/js/umc/modules/schoolusers.js     2019-05-16 10:43:23.871751467 +0200
@@ -105,7 +105,7 @@
                                                return _('never');
                                        } else if (days == 0) {
                                                return _('now');
-                                       } else if (isNan(days)) { // This should never happen!
+                                       } else if (isNaN(days)) { // This should never happen!
                                                return "NaN";
                                        } else if (days == 1) {
                                                return _('in %s day', days);