From 12770291b7198323c7d9dd0fb31f1ed8dcad93c2 Mon Sep 17 00:00:00 2001
From: Justin Ethier <justin.ethier@gmail.com>
Date: Sat, 12 Nov 2016 06:02:33 +0000
Subject: [PATCH] Issue #132 - Protect against hang

---
 scheme/cyclone/cps-optimizations.sld | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/scheme/cyclone/cps-optimizations.sld b/scheme/cyclone/cps-optimizations.sld
index afcafcff..370a0dfb 100644
--- a/scheme/cyclone/cps-optimizations.sld
+++ b/scheme/cyclone/cps-optimizations.sld
@@ -96,7 +96,8 @@
           ;; Follow references
           ((ref? value)
            (with-var! value (lambda (var)
-             (update-lambda-atv! (cons value syms) (adbv:assigned-value var)))))
+             (if (not (member value syms))
+                 (update-lambda-atv! (cons value syms) (adbv:assigned-value var))))))
           (else
             #f))
       )