diff --git a/BUGS b/BUGS
index a16a05821..2375d6d71 100644
--- a/BUGS
+++ b/BUGS
@@ -87,6 +87,8 @@ MacOS X:
 	are not generated, and the keyboard cannot be grabbed.
 
 	MacOS X seems to have a broken pthread_cancel() implementation.
+	Actually, it just only has one cancellation point defined.
+	http://lists.apple.com/archives/darwin-development/2004/Jun/24/killingapthread.001.txt
 
 FreeBSD:
 	pthread_cancel() isn't supported by FreeBSD 3.X, so threads don't