diff --git a/src/Calendar/index.ts b/src/Calendar/index.ts
index 1229d31..cfe2a45 100644
--- a/src/Calendar/index.ts
+++ b/src/Calendar/index.ts
@@ -1,3 +1,4 @@
+import { GroupTypes } from "../types";
 import Config from "../Config/Config";
 import Events from "../Events/";
 import EventGrouping from "../EventGrouping";
@@ -11,7 +12,7 @@ export default class Calendar {
   constructor(json) {
     this.jsonContent = json;
     this.config = new Config({
-      groupTypes: json["group"].charAt(0),
+      groupTypes: json["group"] ? json["group"].charAt(0) : GroupTypes.Day,
     });
     this.events = new Events(json["events"]);
     this.eventGrouping = new EventGrouping(
diff --git a/src/Config/Config.ts b/src/Config/Config.ts
index fa65db6..60c7298 100644
--- a/src/Config/Config.ts
+++ b/src/Config/Config.ts
@@ -4,6 +4,6 @@ export default class Config {
   groupTypes: GroupTypes;
 
   constructor({ groupTypes }) {
-    this.groupTypes = groupTypes.toUpperCase() || GroupTypes.Week;
+    this.groupTypes = groupTypes.toUpperCase();
   }
 }