diff --git a/input.c b/input.c
index 705fc7af..3bb9eaba 100644
--- a/input.c
+++ b/input.c
@@ -743,7 +743,8 @@ wl_pointer_leave(void *data, struct wl_pointer *wl_pointer,
     } else {
         if (surface != NULL) {
             /* Sway 1.4 sends this event with a NULL surface when we destroy the window */
-            const struct wl_window *win = wl_surface_get_user_data(surface);
+            const struct wl_window *win __attribute__((unused))
+                = wl_surface_get_user_data(surface);
             assert(old_moused == win->term);
         }
         old_moused->active_surface = TERM_SURF_NONE;