--- rxvt-unicode/src/main.C	2006/01/06 05:37:59	1.164
+++ rxvt-unicode/src/main.C	2006/01/08 00:20:12	1.165
@@ -489,6 +489,9 @@
 #endif
 
 #if ENABLE_PERL
+  if (!rs[Rs_perl_ext_1])
+    rs[Rs_perl_ext_1] = "default";
+
   if ((rs[Rs_perl_ext_1] && *rs[Rs_perl_ext_1])
       || (rs[Rs_perl_ext_2] && *rs[Rs_perl_ext_2])
       || (rs[Rs_perl_eval] && *rs[Rs_perl_eval]))