diff --git a/app/api/calendar/route.ts b/app/api/calendar/route.ts
index f6c8e3f..5f64bec 100644
--- a/app/api/calendar/route.ts
+++ b/app/api/calendar/route.ts
@@ -4,6 +4,12 @@ import { google } from 'googleapis'
 import * as fs from 'fs'
 import * as path from 'path'
 
+function nextDayISO(date: string): string {
+  const d = new Date(`${date}T00:00:00Z`)
+  d.setUTCDate(d.getUTCDate() + 1)
+  return d.toISOString().slice(0, 10)
+}
+
 function getAuth(readonly = true) {
   const scopes = readonly
     ? ['https://www.googleapis.com/auth/calendar.readonly']
@@ -134,11 +140,11 @@ export async function POST(req: Request) {
 
   let start: any, end: any
   if (allDay) {
-    start = { date }
-    end = { date }
+    start = { date, dateTime: null }
+    end = { date: nextDayISO(date), dateTime: null }
   } else {
-    start = { dateTime: `${date}T${startTime}:00`, timeZone: 'Europe/Moscow' }
-    end = { dateTime: `${date}T${endTime}:00`, timeZone: 'Europe/Moscow' }
+    start = { dateTime: `${date}T${startTime}:00`, timeZone: 'Europe/Moscow', date: null }
+    end = { dateTime: `${date}T${endTime}:00`, timeZone: 'Europe/Moscow', date: null }
   }
 
   try {
@@ -181,11 +187,11 @@ export async function PUT(req: Request) {
 
   let start: any, end: any
   if (allDay) {
-    start = { date }
-    end = { date }
+    start = { date, dateTime: null }
+    end = { date: nextDayISO(date), dateTime: null }
   } else {
-    start = { dateTime: `${date}T${startTime}:00`, timeZone: 'Europe/Moscow' }
-    end = { dateTime: `${date}T${endTime}:00`, timeZone: 'Europe/Moscow' }
+    start = { dateTime: `${date}T${startTime}:00`, timeZone: 'Europe/Moscow', date: null }
+    end = { dateTime: `${date}T${endTime}:00`, timeZone: 'Europe/Moscow', date: null }
   }
 
   try {