diff --git a/src/floating.c b/src/floating.c
index 65a2810a..17a99638 100644
--- a/src/floating.c
+++ b/src/floating.c
@@ -621,7 +621,7 @@ void floating_resize_window(Con *con, const bool proportional,
         con->scratchpad_state = SCRATCHPAD_CHANGED;
 }
 
-/* As endorsed by “ASSOCIATING CUSTOM DATA WITH A WATCHER” in ev(3) */
+/* Custom data structure used to track dragging-related events. */
 struct drag_x11_cb {
     ev_check check;
 
@@ -643,7 +643,7 @@ struct drag_x11_cb {
 };
 
 static void xcb_drag_check_cb(EV_P_ ev_check *w, int revents) {
-    struct drag_x11_cb *dragloop = (struct drag_x11_cb *)w;
+    struct drag_x11_cb *dragloop = (struct drag_x11_cb *)w->data;
     xcb_motion_notify_event_t *last_motion_notify = NULL;
     xcb_generic_event_t *event;
 
@@ -782,16 +782,18 @@ drag_result_t drag_pointer(Con *con, const xcb_button_press_event_t *event, xcb_
         .callback = callback,
         .extra = extra,
     };
+    ev_check *check = &loop.check;
     if (con)
         loop.old_rect = con->rect;
-    ev_check_init(&loop.check, xcb_drag_check_cb);
+    ev_check_init(check, xcb_drag_check_cb);
+    check->data = &loop;
     main_set_x11_cb(false);
-    ev_check_start(main_loop, &loop.check);
+    ev_check_start(main_loop, check);
 
     while (loop.result == DRAGGING)
         ev_run(main_loop, EVRUN_ONCE);
 
-    ev_check_stop(main_loop, &loop.check);
+    ev_check_stop(main_loop, check);
     main_set_x11_cb(true);
 
     xcb_ungrab_keyboard(conn, XCB_CURRENT_TIME);