diff --git a/components/script/dom/mediastream.rs b/components/script/dom/mediastream.rs
index 395abd95ab6..38a9ce5f652 100644
--- a/components/script/dom/mediastream.rs
+++ b/components/script/dom/mediastream.rs
@@ -83,4 +83,19 @@ impl MediaStreamMethods for MediaStream {
             .find(|x| x.id().id().to_string() == &*id)
             .map(|x| DomRoot::from_ref(&**x))
     }
+
+    /// https://w3c.github.io/mediacapture-main/#dom-mediastream-addtrack
+    fn AddTrack(&self, track: &MediaStreamTrack) {
+        let existing = self.tracks.borrow().iter().find(|x| *x == &track).is_some();
+
+        if existing {
+            return;
+        }
+        self.add_track(track)
+    }
+
+    /// https://w3c.github.io/mediacapture-main/#dom-mediastream-removetrack
+    fn RemoveTrack(&self, track: &MediaStreamTrack) {
+        self.tracks.borrow_mut().retain(|x| *x != track);
+    }
 }
diff --git a/components/script/dom/webidls/MediaStream.webidl b/components/script/dom/webidls/MediaStream.webidl
index 10b151225de..5b991f2e53a 100644
--- a/components/script/dom/webidls/MediaStream.webidl
+++ b/components/script/dom/webidls/MediaStream.webidl
@@ -15,8 +15,8 @@ interface MediaStream : EventTarget {
     sequence<MediaStreamTrack> getVideoTracks();
     sequence<MediaStreamTrack> getTracks();
     MediaStreamTrack? getTrackById(DOMString trackId);
-    // void addTrack(MediaStreamTrack track);
-    // void removeTrack(MediaStreamTrack track);
+    void addTrack(MediaStreamTrack track);
+    void removeTrack(MediaStreamTrack track);
     // MediaStream clone();
     // readonly        attribute boolean active;
     //                 attribute EventHandler onaddtrack;