From 4a8c8a3a7591a7c79149e8289537c3eb1b1e73c8 Mon Sep 17 00:00:00 2001
From: Alex Shinn <ashinn@users.noreply.github.com>
Date: Sat, 7 Jul 2012 14:17:02 +0900
Subject: [PATCH] Fix for string-concatenate on empty lists.

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

diff --git a/sexp.c b/sexp.c
index a67d9a26..242b1f33 100644
--- a/sexp.c
+++ b/sexp.c
@@ -1051,7 +1051,7 @@ sexp sexp_string_concatenate_op (sexp ctx, sexp self, sexp_sint_t n, sexp str_ls
       return sexp_type_exception(ctx, self, SEXP_STRING, sexp_car(ls));
     else
       len += sexp_string_length(sexp_car(ls));
-  if (sexp_stringp(sep) && ((sep_len=sexp_string_length(sep)) > 0)) {
+  if ((i > 0) && sexp_stringp(sep) && ((sep_len=sexp_string_length(sep)) > 0)) {
     csep = sexp_string_data(sep);
     len += sep_len*(i-1);
   }