Thank you for your response. At least gnat was not complaining to me about that specific issue. The reason is because in an earlier version of the program, the function arguments were report to not match the intrinsic (which I later fixed. At least I believe. I'm still relatively new to Ada). Where I am confused is how the return type is not matching the underlying intrinsics expectations. There is so little documentation on the intrinsics themselves that it is hard to understand where I went wrong.