2 files changed, 3 insertions, 4 deletions
diff --git a/components/script/dom/mouseevent.rs b/components/script/dom/mouseevent.rs
index 9e0b7119326..e51b8391ee0 100644
--- a/components/script/dom/mouseevent.rs
+++ b/components/script/dom/mouseevent.rs
@@ -160,11 +160,11 @@ impl<'a> MouseEventMethods for &'a MouseEvent {
     //  - https://github.com/servo/servo/issues/6643
     //  - https://bugzilla.mozilla.org/show_bug.cgi?id=1186125
     // This returns the same result as current gecko.
-    fn GetWhich(self) -> Fallible<i32> {
+    fn Which(self) -> i32 {
         if opts::experimental_enabled() {
-            Ok((self.button.get() + 1) as i32)
+            (self.button.get() + 1) as i32
         } else {
-            Err(NotSupported)
+            0
         }
     }
 
diff --git a/components/script/dom/webidls/MouseEvent.webidl b/components/script/dom/webidls/MouseEvent.webidl
index be3abc86cdd..f9be1e64ed0 100644
--- a/components/script/dom/webidls/MouseEvent.webidl
+++ b/components/script/dom/webidls/MouseEvent.webidl
@@ -20,7 +20,6 @@ interface MouseEvent : UIEvent {
     //readonly    attribute unsigned short buttons;
     //boolean getModifierState (DOMString keyArg);
 
-    [Throws]
     readonly    attribute long           which;
 };