diff --git a/json_tokener.c b/json_tokener.c
index 8b1e3e6..98611d6 100644
--- a/json_tokener.c
+++ b/json_tokener.c
@@ -253,6 +253,9 @@ struct json_object* json_tokener_parse_ex(struct json_tokener *tok,
      the string length is less than INT32_MAX (2GB) */
   if ((len < -1) || (len == -1 && strlen(str) > INT32_MAX)) {
     tok->err = json_tokener_error_size;
+#ifdef HAVE_SETLOCALE
+  free(oldlocale);
+#endif
     return NULL;
   }