diff --git a/CHANGES.md b/CHANGES.md
index 92800e310..837bccc2c 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -4,6 +4,8 @@ wavesurfer.js changelog
 4.0.0 (21.06.2020)
 ------------------
 
+- Fixes for event handling with certain plugins (regions, microphone).
+  The crash would have involved '_disabledEventEmissions'
 - Fixed mediaelement-webaudio playback under Safari (#1964)
 - Fixed the `destroy` method of the `MediaElementWebAudio` backend. Instead of
   destroying only the media element, the audio nodes are disconnected and the
diff --git a/src/util/observer.js b/src/util/observer.js
index e285cee93..444fd8bf3 100644
--- a/src/util/observer.js
+++ b/src/util/observer.js
@@ -115,6 +115,15 @@ export default class Observer {
         this._disabledEventEmissions = eventNames;
     }
 
+    /**
+     * plugins borrow part of this class without calling the constructor,
+     * so we have to be careful about _disabledEventEmissions
+     */
+
+    _isDisabledEventEmission(event) {
+        return this._disabledEventEmissions && this._disabledEventEmissions.includes(event);
+    }
+
     /**
      * Manually fire an event
      *
@@ -122,7 +131,7 @@ export default class Observer {
      * @param {...any} args The arguments with which to call the listeners
      */
     fireEvent(event, ...args) {
-        if (!this.handlers || this._disabledEventEmissions.includes(event)) {
+        if (!this.handlers || this._isDisabledEventEmission(event)) {
             return;
         }