diff --git a/src/typings/interfaces/event.interface.ts b/src/typings/interfaces/event.interface.ts
index fd4ebe36..c6321ba8 100644
--- a/src/typings/interfaces/event.interface.ts
+++ b/src/typings/interfaces/event.interface.ts
@@ -1,4 +1,4 @@
-import type { modeType } from '../types';
+import type {extendedModeType, modeType} from '../types';
 
 export type eventId = string | number;
 
@@ -25,7 +25,7 @@ export interface eventInterface {
   isEditable?: boolean; // If true, the event has delete- and edit icons in Event-Flyout. Can also be dragged and dropped.
   disableDnD?: modeType[]; // Disable Drag and Drop for this event, in the modes specified
   disableResize?: modeType[]; // Disable Resize for this event, in the modes specified
-  isCustom?: boolean | modeType[]; // If true, the event expects to be displayed using the event slot. It can also be specified as an array, of all modes, where the event should be displayed using the event slot.
+  isCustom?: boolean | extendedModeType[]; // If true, the event expects to be displayed using the event slot. It can also be specified as an array, of all modes, where the event should be displayed using the event slot.
 
   // These are properties that should never be fed into the Calendar
   // Instead, they are assigned to events, in order to for example position/style them correctly
diff --git a/src/typings/types.ts b/src/typings/types.ts
index 07205d7c..1a7258af 100644
--- a/src/typings/types.ts
+++ b/src/typings/types.ts
@@ -9,7 +9,10 @@ export interface DOMRect {
   y: number;
 }
 
-export type modeType = "day" | "week" | "month" | "agenda";
+export type modeType = "day" | "week" | "month";
+
+// Includes the pseudo-mode "agenda", which is the alternative to the month mode on small screens
+export type extendedModeType = modeType | "agenda";
 
 export enum DRAG_N_RESIZE_DIRECTION {
   BACKWARDS = "backwards",