In the program_options library, command-line parsing functions that take (argc, argv) arguments do not check for a zero argc. Thus, when argc is zero, the iterators passed to the vector constructor have first > last, which results in undefined behaviour. Patches are attached which address this (minimally, simply by treating argc as 1 when it's 0, since argv[0] is never used). According to the execve reference in Open Group Base Specifications Issue 6: Early proposals required that the value of argc passed to main() be "one or greater". This was driven by the same requirement in drafts of the ISO C standard. In fact, historical implementations have passed a value of zero when no arguments are supplied to the caller of the exec functions. This requirement was removed from the ISO C standard and subsequently removed from this volume of IEEE Std 1003.1-2001 as well. In practice, some operating systems, notably Linux, still do this, as aptly demonstrated with the following program: #include <errno.h> #include <stdio.h> #include <string.h> #include <unistd.h> int main(int argc, char **argv) { char *empty = (char *) 0; if (argc != 2) { fprintf(stderr, "usage: %s program\n", argc ? argv[0] : "(null)"); return 1; } execve(argv[1], &empty, &empty); fprintf(stderr, "Cannot run %s: %s\n", argv[1], strerror(errno)); return 1; } Then you can test with your favourite :-) programs to see how they behave (I've called the program zeroargc in the examples below): $ ./zeroargc usage: ./zeroargc program $ ./zeroargc ./zeroargc usage: (null) program Cheers, Chris.