diff --git a/src/app/components/calendar/calendar.ts b/src/app/components/calendar/calendar.ts
index 62d2c4274e5..c68f731ab8a 100644
--- a/src/app/components/calendar/calendar.ts
+++ b/src/app/components/calendar/calendar.ts
@@ -1643,7 +1643,7 @@ export class Calendar implements OnInit, OnDestroy, ControlValueAccessor {
     }
 
     formatDateKey(date: Date): string {
-        return `${date.getFullYear()}-${date.getMonth() + 1}-${date.getDate()}`;
+        return `${date.getFullYear()}-${date.getMonth()}-${date.getDate()}`;
     }
 
     setCurrentHourPM(hours: number) {