diff --git a/components/calendar/calendar-client.tsx b/components/calendar/calendar-client.tsx
index 1533bc16..820d3a40 100644
--- a/components/calendar/calendar-client.tsx
+++ b/components/calendar/calendar-client.tsx
@@ -1074,7 +1074,7 @@ export function CalendarClient({ initialCalendars, userId, userProfile }: Calend
                         <div className="flex items-center gap-1.5 text-xs text-white">
                           {!arg.event.allDay && (
                             <span className="font-medium whitespace-nowrap shrink-0">
-                              {new Date(arg.event.start).toLocaleTimeString('fr-FR', {
+                              {arg.event.start && new Date(arg.event.start).toLocaleTimeString('fr-FR', {
                                 hour: '2-digit',
                                 minute: '2-digit'
                               })}
@@ -1091,7 +1091,7 @@ export function CalendarClient({ initialCalendars, userId, userProfile }: Calend
                         <p className="font-medium">{arg.event.title}</p>
                         {!arg.event.allDay && (
                           <p className="text-xs text-gray-400 mt-1">
-                            {new Date(arg.event.start).toLocaleTimeString('fr-FR', {
+                            {arg.event.start && new Date(arg.event.start).toLocaleTimeString('fr-FR', {
                               hour: '2-digit',
                               minute: '2-digit'
                             })}