diff --git a/src/api/XRInputSourceEvent.js b/src/api/XRInputSourceEvent.js
index f934bd9..93f5f01 100644
--- a/src/api/XRInputSourceEvent.js
+++ b/src/api/XRInputSourceEvent.js
@@ -26,6 +26,9 @@ export default class XRInputSourceEvent extends Event {
       frame: eventInitDict.frame,
       inputSource: eventInitDict.inputSource
     };
+
+    // safari bug:  super() seems to return object of type Event, with Event as prototype
+    Object.setPrototypeOf(this, XRInputSourceEvent.prototype);
   }
 
   /**
diff --git a/src/api/XRInputSourcesChangeEvent.js b/src/api/XRInputSourcesChangeEvent.js
index a03a65c..f87a3a4 100644
--- a/src/api/XRInputSourcesChangeEvent.js
+++ b/src/api/XRInputSourcesChangeEvent.js
@@ -27,6 +27,8 @@ export default class XRInputSourcesChangeEvent extends Event {
       added: eventInitDict.added,
       removed: eventInitDict.removed
     };
+    // safari bug:  super() seems to return object of type Event, with Event as prototype
+    Object.setPrototypeOf(this, XRInputSourcesChangeEvent.prototype);
   }
 
   /**
diff --git a/src/api/XRReferenceSpaceEvent.js b/src/api/XRReferenceSpaceEvent.js
index 3d7398b..49905ed 100644
--- a/src/api/XRReferenceSpaceEvent.js
+++ b/src/api/XRReferenceSpaceEvent.js
@@ -26,6 +26,8 @@ export default class XRReferenceSpaceEvent extends Event {
       referenceSpace: eventInitDict.referenceSpace,
       transform: eventInitDict.transform || null
     };
+    // safari bug:  super() seems to return object of type Event, with Event as prototype
+    Object.setPrototypeOf(this, XRReferenceSpaceEvent.prototype);
   }
 
   /**
diff --git a/src/api/XRSessionEvent.js b/src/api/XRSessionEvent.js
index c093d8b..8428a81 100644
--- a/src/api/XRSessionEvent.js
+++ b/src/api/XRSessionEvent.js
@@ -25,6 +25,9 @@ export default class XRSessionEvent extends Event {
     this[PRIVATE] = {
       session: eventInitDict.session
     };
+
+    // safari bug:  super() seems to return object of type Event, with Event as prototype
+    Object.setPrototypeOf(this, XRSessionEvent.prototype);
   }
 
   /**