diff --git a/src/openrct2/interface/window.c b/src/openrct2/interface/window.c
index 564ad41bd3..285459740d 100644
--- a/src/openrct2/interface/window.c
+++ b/src/openrct2/interface/window.c
@@ -1932,7 +1932,7 @@ void window_event_resize_call(rct_window *w)
 void window_event_mouse_down_call(rct_window *w, rct_widgetindex widgetIndex)
 {
     if (w->event_handlers->mouse_down != NULL)
-        w->event_handlers->mouse_down(widgetIndex, w, &w->widgets[widgetIndex]);
+        w->event_handlers->mouse_down(w, widgetIndex, &w->widgets[widgetIndex]);
 }
 
 void window_event_dropdown_call(rct_window *w, rct_widgetindex widgetIndex, sint32 dropdownIndex)
diff --git a/src/openrct2/interface/window.h b/src/openrct2/interface/window.h
index f42ddcc793..ace7c20411 100644
--- a/src/openrct2/interface/window.h
+++ b/src/openrct2/interface/window.h
@@ -155,7 +155,7 @@ typedef struct rct_window_event_list {
     void (*close)(struct rct_window*);
     void (*mouse_up)(struct rct_window*, rct_widgetindex);
     void (*resize)(struct rct_window*);
-    void (*mouse_down)(rct_widgetindex, struct rct_window*, rct_widget*);
+    void (*mouse_down)(struct rct_window*, rct_widgetindex, rct_widget*);
     void (*dropdown)(struct rct_window*, rct_widgetindex, sint32);
     void (*unknown_05)(struct rct_window*);
     void (*update)(struct rct_window*);