diff --git a/public/js/components/Calendar/Weeks.js b/public/js/components/Calendar/Weeks.js
index 6a7c32a58..530cfe90e 100644
--- a/public/js/components/Calendar/Weeks.js
+++ b/public/js/components/Calendar/Weeks.js
@@ -9,11 +9,11 @@ export default {
 		'focusDate'
 	],
 	data() {
-		return {
-			weeks: [...Array(this.focusDate.numWeeks).keys()].map(i => i+1)
-		}
 	},
 	computed: {
+		weeks(){
+			return [...Array(this.focusDate.numWeeks).keys()].map(i => i + 1);
+		},
 		title() {
 			return this.focusDate.format({year: 'numeric'});
 		}
@@ -23,11 +23,19 @@ export default {
 			// TODO(chris): test is there a week jump on year select? => yes there is if the same month/day are in different weeks ... should we prevent that?
 			this.focusDate.w = week;
 			this.$emit('updateMode', 'week');
-		}
+		},
+		prev(){
+			this.focusDate.y--;
+			this.focusDate._clean();
+		},
+		next() {
+			this.focusDate.y++;
+			this.focusDate._clean();
+		},
 	},
 	template: `
 	<div class="fhc-calendar-weeks">
-		<calendar-header :title="title" @prev="focusDate.y--" @next="focusDate.y++" @click="$emit('updateMode', 'years')" @updateMode="$emit('updateMode', $event)" />
+		<calendar-header :title="title" @prev="prev" @next="next" @click="$emit('updateMode', 'years')" @updateMode="$emit('updateMode', $event)" />
 		<div class="d-flex flex-wrap">
 			<div v-for="(week, key) in weeks" :key="key" class="d-grid col-2">
 				<button @click="setWeek(week)" class="btn btn-outline-secondary" :class="{'border-0': week != focusDate.w}">
diff --git a/public/js/composables/CalendarDate.js b/public/js/composables/CalendarDate.js
index d31e09add..5f98763a2 100644
--- a/public/js/composables/CalendarDate.js
+++ b/public/js/composables/CalendarDate.js
@@ -128,7 +128,9 @@ class CalendarDate {
 	get numWeeks() {
 		// if the week starts with Monday we have to go 3 days in the past from the start of the next year to get the correct numWeek of the current year
 		// this is because for example 30.12.2024 - 05.01.2025 is the first calendarWeek of 2025 
-		return (new CalendarDate(this.y+1,0,this.weekStart == 1 ? -3 : 0)).w;
+		let lastCalendarWeek = new CalendarDate(this.y + 1, 0, this.weekStart == 1 ? -3 : 0);
+		lastCalendarWeek.weekStart = this.weekStart;
+		return lastCalendarWeek.w;
 	}
 	set(y,m,d,noClean) {