diff --git a/src/ol/Observable.js b/src/ol/Observable.js
index a9d7850ba3..dc7d74bfad 100644
--- a/src/ol/Observable.js
+++ b/src/ol/Observable.js
@@ -13,7 +13,7 @@ import {listen, listenOnce, unlistenByKey} from './events.js';
 
 /***
  * @template {string} Type
- * @typedef {(type: Type[], listener: (event: import("./events/Event").default) => (void|boolean)) => import("./events").EventsKey|Array<import("./events").EventsKey>} CombinedOnSignature
+ * @typedef {(type: Type[], listener: (event: Event|import("./events/Event").default) => (void|boolean)) => import("./events").EventsKey|Array<import("./events").EventsKey>} CombinedOnSignature
  */
 
 /**
@@ -73,7 +73,7 @@ class Observable extends EventTarget {
 
   /**
    * @param {string|Array<string>} type Type.
-   * @param {function(import("./events/Event").default): (void|boolean)} listener Listener.
+   * @param {function(?): (void|boolean)} listener Listener.
    * @return {import("./events.js").EventsKey|Array<import("./events.js").EventsKey>} Event key.
    * @protected
    */
@@ -93,7 +93,7 @@ class Observable extends EventTarget {
 
   /**
    * @param {string|Array<string>} type Type.
-   * @param {function(import("./events/Event").default): (void|boolean)} listener Listener.
+   * @param {function(?): (void|boolean)} listener Listener.
    * @return {import("./events.js").EventsKey|Array<import("./events.js").EventsKey>} Event key.
    * @protected
    */
@@ -116,7 +116,7 @@ class Observable extends EventTarget {
   /**
    * Unlisten for a certain type of event.
    * @param {string|Array<string>} type The event type or array of event types.
-   * @param {function(import("./events/Event").default): (void|boolean)} listener The listener function.
+   * @param {function((Event|import("./events/Event").default)): (void|boolean)} listener The listener function.
    * @api
    */
   un(type, listener) {
@@ -137,7 +137,7 @@ class Observable extends EventTarget {
  * Listen for a certain type of event.
  * @function
  * @param {string|Array<string>} type The event type or array of event types.
- * @param {function(import("./events/Event").default): (void|boolean)} listener The listener function.
+ * @param {function((Event|import("./events/Event").default)): (void|boolean)} listener The listener function.
  * @return {import("./events.js").EventsKey|Array<import("./events.js").EventsKey>} Unique key for the listener. If
  *     called with an array of event types as the first argument, the return
  *     will be an array of keys.
@@ -149,7 +149,7 @@ Observable.prototype.on;
  * Listen once for a certain type of event.
  * @function
  * @param {string|Array<string>} type The event type or array of event types.
- * @param {function(import("./events/Event").default): (void|boolean)} listener The listener function.
+ * @param {function((Event|import("./events/Event").default)): (void|boolean)} listener The listener function.
  * @return {import("./events.js").EventsKey|Array<import("./events.js").EventsKey>} Unique key for the listener. If
  *     called with an array of event types as the first argument, the return
  *     will be an array of keys.