diff --git a/gdk/mir/gdkmireventsource.c b/gdk/mir/gdkmireventsource.c
index e14df97f1e..61ae346077 100644
--- a/gdk/mir/gdkmireventsource.c
+++ b/gdk/mir/gdkmireventsource.c
@@ -162,8 +162,8 @@ generate_scroll_event (GdkWindow *window, gdouble x, gdouble y, gdouble delta_x,
   event->scroll.y = y;
   event->scroll.state = state;
   event->scroll.direction = GDK_SCROLL_SMOOTH;
-  event->scroll.delta_x = delta_x;
-  event->scroll.delta_y = delta_y;
+  event->scroll.delta_x = -delta_x;
+  event->scroll.delta_y = -delta_y;
 
   send_event (window, get_pointer (window), event);
 }