diff --git a/components/compositing/compositor.rs b/components/compositing/compositor.rs
index 4d8cffb75183..136be6eaea0c 100644
--- a/components/compositing/compositor.rs
+++ b/components/compositing/compositor.rs
@@ -1081,6 +1081,7 @@ impl<Window: WindowMethods> IOCompositor<Window> {
                               delta: TypedPoint2D<f32, DevicePixel>,
                               cursor: TypedPoint2D<i32, DevicePixel>) {
         let event_phase = match (self.scroll_in_progress, self.in_scroll_transaction) {
+            (false, None) => ScrollEventPhase::Start,
             (false, Some(last_scroll)) if last_scroll.elapsed() > Duration::from_millis(80) =>
                 ScrollEventPhase::Start,
             (_, _) => ScrollEventPhase::Move(self.scroll_in_progress),