diff --git a/nofile_posix.go b/nofile_test_posix.go
similarity index 65%
rename from nofile_posix.go
rename to nofile_test_posix.go
index 1b07e318f..11ad5583f 100644
--- a/nofile_posix.go
+++ b/nofile_test_posix.go
@@ -7,5 +7,6 @@ import "syscall"
 func curFileLimit() uint64 {
 	var n syscall.Rlimit
 	syscall.Getrlimit(syscall.RLIMIT_NOFILE, &n)
-	return n.Cur
+	// cast because some platforms use int64 (e.g., freebsd)
+	return uint64(n.Cur)
 }
diff --git a/nofile_windows.go b/nofile_test_windows.go
similarity index 100%
rename from nofile_windows.go
rename to nofile_test_windows.go