diff -urp JSON-DWIW-0.21/DWIW.xs JSON-DWIW-0.21-D5cVLF/DWIW.xs
--- JSON-DWIW-0.21/DWIW.xs	2008-01-03 05:40:17.000000000 +0100
+++ JSON-DWIW-0.21-D5cVLF/DWIW.xs	2008-03-15 06:19:03.000000000 +0100
@@ -2522,6 +2522,7 @@ to_json(self_context * self, SV * data_r
           break;
           */
 
+#if PERL_VERSION <= 10
       case SVt_RV:
         /* reference to a reference */
         /* FIXME: implement */
@@ -2533,6 +2534,7 @@ to_json(self_context * self, SV * data_r
           /* sv_catpvn(rsv, "\"\"", 2); */
           return rsv;
         break;
+#endif
 
       case SVt_PVAV: /* array */
           JSON_DEBUG("==========> found array ref");