Hi sabreman, #include <stdio.h> #include <inttypes.h> int main() { uint64_t myVal64 = UINT64_C(18446744073709551615); printf("%" PRId64 "\n", myVal64); return 0; } Hmmm, worked for me. Did you put the "ULL" suffix on your unsigned long long numeric constant? Or use the UINT64_C macro provided by <inttypes.h> or <stdint.h>? HTH, --Eljay