diff --git a/components/script/dom/fakexrdevice.rs b/components/script/dom/fakexrdevice.rs
index b0ebb9f77fc..5b1ca75fb3d 100644
--- a/components/script/dom/fakexrdevice.rs
+++ b/components/script/dom/fakexrdevice.rs
@@ -219,6 +219,17 @@ impl FakeXRDeviceMethods for FakeXRDevice {
         Ok(())
     }
 
+    /// https://immersive-web.github.io/webxr-test-api/#dom-fakexrdevice-clearworld
+    fn ClearWorld(&self) {
+        let _ = self.sender.send(MockDeviceMsg::ClearWorld);
+    }
+
+    /// https://immersive-web.github.io/webxr-test-api/#dom-fakexrdevice-setworld
+    fn SetWorld(&self, world: &FakeXRWorldInit) -> Fallible<()> {
+        let _ = self.sender.send(MockDeviceMsg::SetWorld(get_world(world)?));
+        Ok(())
+    }
+
     /// https://immersive-web.github.io/webxr-test-api/#dom-fakexrdevice-simulatevisibilitychange
     fn SimulateVisibilityChange(&self, v: XRVisibilityState) {
         let v = match v {
diff --git a/components/script/dom/webidls/FakeXRDevice.webidl b/components/script/dom/webidls/FakeXRDevice.webidl
index d30ee2cae62..6349d70963b 100644
--- a/components/script/dom/webidls/FakeXRDevice.webidl
+++ b/components/script/dom/webidls/FakeXRDevice.webidl
@@ -27,8 +27,8 @@ interface FakeXRDevice {
   Promise<void> disconnect();
 
   // Hit test extensions:
-  // void setWorld(FakeXRWorldInit world);
-  // void clearWorld();
+  [Throws] void setWorld(FakeXRWorldInit world);
+  void clearWorld();
 };
 
 // https://immersive-web.github.io/webxr/#dom-xrwebgllayer-getviewport