--- Swap.xs.orig 2009-08-01 12:35:06.000000000 +0200 +++ Swap.xs 2009-08-01 12:35:28.000000000 +0200 @@ -219,7 +219,7 @@ Perl_croak(aTHX_ "Not a reference"); if ((SvREADONLY(r1) && SvIMMORTAL(r1)) || (SvREADONLY(r2) && SvIMMORTAL(r2))) - Perl_croak(aTHX_ PL_no_modify); + Perl_croak(aTHX_ "%s", PL_no_modify); br = NULL; br = sv_move(aTHX_ &t, r1, br); br = sv_move(aTHX_ r1, r2, br);