From 730fdb31117e1467e4cc620c9715596427fd5b5a Mon Sep 17 00:00:00 2001
From: Justin Ethier <justin.ethier@gmail.com>
Date: Tue, 3 May 2016 00:10:59 -0400
Subject: [PATCH] Fix crash when cdr is a value type

---
 runtime.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/runtime.c b/runtime.c
index fad67cf7..0ba26b8c 100644
--- a/runtime.c
+++ b/runtime.c
@@ -789,7 +789,7 @@ static object _Cyc_write(object x, FILE * port)
       break;
     }
 
-    for (tmp = cdr(x); tmp && ((closure) tmp)->tag == pair_tag; tmp = cdr(tmp)) {
+    for (tmp = cdr(x); tmp && !is_value_type(tmp) && ((closure) tmp)->tag == pair_tag; tmp = cdr(tmp)) {
       if (has_cycle == boolean_t) {
         if (i++ > 20)
           break;                /* arbitrary number, for now */