diff --git a/web/typo3conf/ext/ep_theme/Resources/Private/Assets/js/components/Calendar.vue b/web/typo3conf/ext/ep_theme/Resources/Private/Assets/js/components/Calendar.vue
index 9c071cb0..5f7f4935 100644
--- a/web/typo3conf/ext/ep_theme/Resources/Private/Assets/js/components/Calendar.vue
+++ b/web/typo3conf/ext/ep_theme/Resources/Private/Assets/js/components/Calendar.vue
@@ -1,5 +1,5 @@
 <template>
-    <div class="row calendar" :class="{ 'calendar--single': months == 1 }">
+    <div class="row calendar" :class="{ 'calendar--single': isSingleCalendar }">
         <div class="col-xs-12" v-if="showHeader">
             <h2>Belegungskalender {{ hotelName }}</h2>
         </div>
@@ -71,6 +71,11 @@
                 loading: false
             }
         },
+        computed: {
+            isSingleCalendar () {
+                return parseInt(this.months) === 1;
+            }
+        },
         methods: {
             loadCalendar () {
                 let query = {};
@@ -86,11 +91,11 @@
                 });
             },
             next () {
-                this.startDate.add(this.step, 'M');
+                this.startDate = this.startDate.add(this.step, 'month');
                 this.loadCalendar();
             },
             prev () {
-                this.startDate.subtract(this.step, 'M');
+                this.startDate = this.startDate.subtract(this.step, 'month');
                 this.loadCalendar();
             }
         },