# define Nullcv Null(CV*)
#endif
-#define CvSTASH(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_stash
+#define CvSTASH(sv) (0+((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_stash)
+#define CvSTASH_set(cv,st) Perl_cvstash_set(aTHX_ cv, st)
#define CvSTART(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_start_u.xcv_start
#define CvROOT(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_root_u.xcv_root
#define CvXSUB(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_root_u.xcv_xsub