diff --git a/widget/gtk/nsWindow.cpp b/widget/gtk/nsWindow.cpp
index 373fe68db0e9..d40f76bc05d9 100644
--- a/widget/gtk/nsWindow.cpp
+++ b/widget/gtk/nsWindow.cpp
@@ -6596,63 +6596,3 @@ nsWindow::SynthesizeNativeMouseEvent(LayoutDeviceIntPoint aPoint,
 
   return NS_OK;
 }
-
-nsresult
-nsWindow::SynthesizeNativeMouseScrollEvent(mozilla::LayoutDeviceIntPoint aPoint,
-                                           uint32_t aNativeMessage,
-                                           double aDeltaX,
-                                           double aDeltaY,
-                                           double aDeltaZ,
-                                           uint32_t aModifierFlags,
-                                           uint32_t aAdditionalFlags,
-                                           nsIObserver* aObserver)
-{
-  AutoObserverNotifier notifier(aObserver, "mousescrollevent");
-
-  if (!mGdkWindow) {
-    return NS_OK;
-  }
-
-  GdkEvent event;
-  memset(&event, 0, sizeof(GdkEvent));
-  event.type = GDK_SCROLL;
-  event.scroll.window = mGdkWindow;
-  event.scroll.time = GDK_CURRENT_TIME;
-#if (MOZ_WIDGET_GTK == 3)
-  // Get device for event source
-  GdkDisplay* display = gdk_window_get_display(mGdkWindow);
-  GdkDeviceManager *device_manager = gdk_display_get_device_manager(display);
-  event.scroll.device = gdk_device_manager_get_client_pointer(device_manager);
-#endif
-  event.scroll.x_root = aPoint.x;
-  event.scroll.y_root = aPoint.y;
-
-  LayoutDeviceIntPoint pointInWindow = aPoint - WidgetToScreenOffset();
-  event.scroll.x = pointInWindow.x;
-  event.scroll.y = pointInWindow.y;
-
-  // The delta values are backwards on Linux compared to Windows and Cocoa,
-  // hence the negation.
-#if GTK_CHECK_VERSION(3,4,0)
-  // TODO: is this correct? I don't have GTK 3.4+ so I can't check
-  event.scroll.direction = GDK_SCROLL_SMOOTH;
-  event.scroll.delta_x = -aDeltaX;
-  event.scroll.delta_y = -aDeltaY;
-#else
-  if (aDeltaX < 0) {
-    event.scroll.direction = GDK_SCROLL_RIGHT;
-  } else if (aDeltaX > 0) {
-    event.scroll.direction = GDK_SCROLL_LEFT;
-  } else if (aDeltaY < 0) {
-    event.scroll.direction = GDK_SCROLL_DOWN;
-  } else if (aDeltaY > 0) {
-    event.scroll.direction = GDK_SCROLL_UP;
-  } else {
-    return NS_OK;
-  }
-#endif
-
-  gdk_event_put(&event);
-
-  return NS_OK;
-}
diff --git a/widget/gtk/nsWindow.h b/widget/gtk/nsWindow.h
index ad94df7c8424..cc2a0efcada3 100644
--- a/widget/gtk/nsWindow.h
+++ b/widget/gtk/nsWindow.h
@@ -306,15 +306,6 @@ public:
                                                nsIObserver* aObserver) override
     { return SynthesizeNativeMouseEvent(aPoint, GDK_MOTION_NOTIFY, 0, aObserver); }
 
-    virtual nsresult SynthesizeNativeMouseScrollEvent(mozilla::LayoutDeviceIntPoint aPoint,
-                                                      uint32_t aNativeMessage,
-                                                      double aDeltaX,
-                                                      double aDeltaY,
-                                                      double aDeltaZ,
-                                                      uint32_t aModifierFlags,
-                                                      uint32_t aAdditionalFlags,
-                                                      nsIObserver* aObserver) override;
-
 protected:
     virtual ~nsWindow();