Rounding value in swift results into a segmentation fault

Question

I'm trying to round the following formula, if I uncomment one of the lines of code that should round my binet variable the program errors.

The return value will be casted to an int, this will truncate the float but is not preferable in this case.

#if os(macOS) || os(iOS)
import Darwin
#elseif os(Linux) || CYGWIN
import Glibc
#endif

func fibFormula(_ n: Int) -> Int {
  var binet = pow((pow(5, 0.5) + 1) / 2, Float(n)) / pow(5, 0.5)
  // binet = round(binet)
  // binet.round();
  return Int(binet)
}

print(fibFormula(5)) // Should output 5

Error:

Stack dump:
0.  Program arguments: /usr/bin/swift -frontend -interpret fib.swift -disable-objc-interop -color-diagnostics -module-name fib -- 5 
/usr/bin/swift(+0x42e1b54)[0x55f476d0bb54]
/usr/bin/swift(+0x42df93e)[0x55f476d0993e]
/usr/bin/swift(+0x42e1d12)[0x55f476d0bd12]
/usr/lib/libpthread.so.0(+0x13d00)[0x7fdf098bfd00]
[0x7fdf099243fa]
[0x7fdf099241ea]
/usr/bin/swift(+0xd7f095)[0x55f4737a9095]
/usr/bin/swift(+0xd82fe0)[0x55f4737acfe0]
/usr/bin/swift(+0x607d13)[0x55f473031d13]
/usr/bin/swift(+0x5df088)[0x55f473009088]
/usr/bin/swift(+0x5da4c2)[0x55f4730044c2]
/usr/bin/swift(+0x58bea1)[0x55f472fb5ea1]
/usr/lib/libc.so.6(__libc_start_main+0xf3)[0x7fdf090f7ee3]
/usr/bin/swift(+0x58a2be)[0x55f472fb42be]
Segmentation fault (core dumped)

Can anyone help me resolve this error? I'm pretty new to swift and I'm using Linux.

Edit: When I try my code in a sandbox it works with using the round function. Maybe this is a Glibc issue?

A more readable version of the formula (also different method, same results):

import Glibc
func fibFormula2(_ n: Int) -> Int {
  let sqrt5 = sqrt(5)
  let phi = (sqrt5 + 1) / 2
  let binet = pow(phi, Double(n)) / sqrt5
  return Int(round(binet))
}
print(fibFormula2(5)) // Should output 5