--- JSON-XS/XS.xs	2007/03/29 02:45:49	1.21
+++ JSON-XS/XS.xs	2007/03/31 14:20:06	1.22
@@ -968,6 +968,8 @@
 {
   SV *sv;
 
+  SvUPGRADE (string, SVt_PV);
+
   if (flags & F_UTF8)
     sv_utf8_downgrade (string, 0);
   else