--- sv.c.orig	2011-05-08 05:10:08.000000000 +0200
+++ sv.c	2011-06-06 16:12:07.421329360 +0200
@@ -6638,6 +6638,18 @@ Perl_sv_clear(pTHX_ SV *const orig_sv)
 
         assert(SvREFCNT(sv) == 0);
         assert(!SvIS_FREED(sv));
+
+	if (type == SVTYPEMASK) {
+	    /* in some bad cases, scalar is freed a second time,
+	       resulting in a segfault (mdvbz#34505) in mg_free(sv) below.
+
+	       perl HEAD has an assert (http://public.activestate.com/cgi-bin/perlbrowse/p/32788),
+	       but since we can't reproduce and it's seems hard to fix those cases,
+	       (as http://rt.perl.org/rt3/Public/Bug/Display.html?id=50142 seems to say ??)
+	       we need to workaround... */
+	    return;
+	}
+
 #if NVSIZE <= IVSIZE
         if (type <= SVt_NV) {
 #else