diff --git a/hello.asm b/hello.asm
index ddf817d..8980241 100644
--- a/hello.asm
+++ b/hello.asm
@@ -252,6 +252,8 @@ event_mouse:
 ;  bx = Y
 ;  cx = X
 ;  dl = mouse buttons
+; out:
+;  clobbers ax
 event_click:
 	; This is not a true event passed into our event handler, but
 	; rather one we've synthetized from the mouse event