diff --git a/src/message.c b/src/message.c
index c13a94d..af91bd8 100644
--- a/src/message.c
+++ b/src/message.c
@@ -3752,6 +3752,8 @@
  * Other buttons- use your imagination!
  * A '&' in a button name becomes a shortcut, so each '&' should be before a
  * different letter.
+ *
+ * Returns 0 if cancelled, otherwise the nth button (1-indexed).
  */
     int
 do_dialog(