"Unbound module Pervasives" error when using OCaml build system in Sublime Text 3

I'm trying to create a build system for OCaml in sublime text 3 on Windows 8.1. I installed OCaml via opam in Cygwin and typed the following into the OCaml.sublime-build file:

{
"cmd": ["C:/OCaml64/home/LENOVO/.opam/4.05.0+mingw64c/bin/ocaml.exe", "$file"],
"file_regex": "^[ ]*File \"(...*?)\", line ([0-9]*)",
"selector": "source.ml"
}

I'm trying the build system out with a test.ml that contains print_endline "hello world";;. I can run the command directly from the terminal with the ocaml interactive command line or using ocaml test.ml. But when I open the file in Sublime Text 3 and run Ctrl-B, I get the following error:

File "command line", line 1:
Error: Unbound module Pervasives

I searched for this error online but could not find much that applies to my situation. Any help is much appreciated!