diff --git a/desktop-shell/shell.c b/desktop-shell/shell.c
index cd269a8..27a6ca3 100644
--- a/desktop-shell/shell.c
+++ b/desktop-shell/shell.c
@@ -1869,7 +1869,7 @@
 
 /*
  * Returns the bounding box of a surface and all its sub-surfaces,
- * in the surface coordinates system. */
+ * in surface-local coordinates. */
 static void
 surface_subsurfaces_boundingbox(struct weston_surface *surface, int32_t *x,
 				int32_t *y, int32_t *w, int32_t *h) {