Fixes #645

diff --git a/json_tokener.c b/json_tokener.c
index 63e02a147cf8ea89d180837c8d9a3e6abcf68196..6527270dd475e058a99f029d52789cec501206ba 100644 (file)
--- a/json_tokener.c
+++ b/json_tokener.c
@@ -430,7 +430,7 @@ struct json_object *json_tokener_parse_ex(struct json_tokener *tok, const char *
                        {
                                char inf_char = *str;
                                if (!(tok->flags & JSON_TOKENER_STRICT))
-                                       inf_char = tolower((int)*str);
+                                       inf_char = tolower((unsigned char)*str);
                                if (inf_char != _json_inf_str[tok->st_pos])
                                {
                                        tok->err = json_tokener_error_parse_unexpected;