From 4e5b8e8d0ef673fb09c693481e537d9db67175be Mon Sep 17 00:00:00 2001
From: Leonardo de Moura <leonardo@microsoft.com>
Date: Tue, 31 May 2016 16:19:01 -0700
Subject: [PATCH] fix(library/string): conversion from std::string to lean expr

---
 src/library/string.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/library/string.cpp b/src/library/string.cpp
index 63ffa5a7e8..ba0c5a243b 100644
--- a/src/library/string.cpp
+++ b/src/library/string.cpp
@@ -140,7 +140,7 @@ void finalize_string() {
 expr from_string_core(std::string const & s) {
     expr r = *g_empty;
     for (unsigned i = 0; i < s.size(); i++) {
-        expr n = to_nat_expr(mpz(s[i]));
+        expr n = to_nat_expr(mpz(static_cast<unsigned char>(s[i])));
         expr c = mk_app(*g_char_of_nat, n);
         r = mk_app(*g_str, c, r);
     }