lanx:$ perl -MDevel::Peek -E'$x+=2**$_ for 0..53;Dump ($x);Dump($x+1);say "*** WTF *** " if $x == $x+1' SV = PVNV(0x5ea09827d340) at 0x5ea0982abd00 REFCNT = 1 FLAGS = (NOK,pNOK) IV = 9007199254740991 NV = 18014398509481984 PV = 0 SV = NV(0x5ea09830cb18) at 0x5ea09830cb30 REFCNT = 1 FLAGS = (PADTMP,NOK,pNOK) NV = 18014398509481984 *** WTF ***