diff --git a/crates/nu-system/src/foreground.rs b/crates/nu-system/src/foreground.rs
index a474b6aaea..953b7c9818 100644
--- a/crates/nu-system/src/foreground.rs
+++ b/crates/nu-system/src/foreground.rs
@@ -28,9 +28,9 @@ impl ForegroundProcess {
     }
 
     pub fn spawn(&mut self) -> std::io::Result<ForegroundChild> {
-        fg_process_setup::prepare_to_foreground(&mut self.inner);
+        prepare_to_foreground(&mut self.inner);
         self.inner.spawn().map(|child| {
-            fg_process_setup::set_foreground(&child);
+            set_foreground(&child);
             ForegroundChild { inner: child }
         })
     }
@@ -45,67 +45,67 @@ impl AsMut<Child> for ForegroundChild {
 impl Drop for ForegroundChild {
     fn drop(&mut self) {
         // It's ok to use here because we have called `set_foreground` during creation.
-        unsafe { fg_process_setup::reset_foreground_id() }
+        unsafe { reset_foreground_id() }
     }
 }
 
+#[cfg(target_family = "unix")]
+use std::os::unix::prelude::CommandExt;
+
 // It's a simpler version of fish shell's external process handling.
 //
 // For more information, please check `child_setup_process` function in fish shell.
 // https://github.com/fish-shell/fish-shell/blob/3f90efca38079922b4b21707001d7bb9630107eb/src/postfork.cpp#L140
-#[cfg(target_family = "unix")]
-mod fg_process_setup {
-    use std::os::unix::prelude::CommandExt;
-    pub fn prepare_to_foreground(external_command: &mut std::process::Command) {
-        unsafe {
-            libc::signal(libc::SIGTTOU, libc::SIG_IGN);
-            libc::signal(libc::SIGTTIN, libc::SIG_IGN);
+//
+// The function does nothing on windows.
+fn prepare_to_foreground(external_command: &mut std::process::Command) {
+    #[cfg(target_family = "unix")]
+    unsafe {
+        libc::signal(libc::SIGTTOU, libc::SIG_IGN);
+        libc::signal(libc::SIGTTIN, libc::SIG_IGN);
 
-            // Safety:
-            // POSIX only allows async-signal-safe functions to be called.
-            // And `setpgid` is async-signal-safe function according to:
-            // https://manpages.ubuntu.com/manpages/bionic/man7/signal-safety.7.html
-            // So we're ok to invoke `libc::setpgid` inside `pre_exec`.
-            external_command.pre_exec(|| {
-                // make the command startup with new process group.
-                // The process group id must be the same as external commands' pid.
-                // Or else we'll failed to set it as foreground process.
-                // For more information, check `fork_child_for_process` function:
-                // https://github.com/fish-shell/fish-shell/blob/023042098396aa450d2c4ea1eb9341312de23126/src/exec.cpp#L398
-                libc::setpgid(0, 0);
-                Ok(())
-            });
-        }
+        // Safety:
+        // POSIX only allows async-signal-safe functions to be called.
+        // And `setpgid` is async-signal-safe function according to:
+        // https://manpages.ubuntu.com/manpages/bionic/man7/signal-safety.7.html
+        // So we're ok to invoke `libc::setpgid` inside `pre_exec`.
+        external_command.pre_exec(|| {
+            // make the command startup with new process group.
+            // The process group id must be the same as external commands' pid.
+            // Or else we'll failed to set it as foreground process.
+            // For more information, check `fork_child_for_process` function:
+            // https://github.com/fish-shell/fish-shell/blob/023042098396aa450d2c4ea1eb9341312de23126/src/exec.cpp#L398
+            libc::setpgid(0, 0);
+            Ok(())
+        });
     }
+}
 
-    // If `prepare_to_foreground` function is not called, the function will fail with silence and do nothing.
-    pub fn set_foreground(process: &std::process::Child) {
-        // it's ok to use unsafe here
-        // the implementaion here is just the same as
-        // https://docs.rs/nix/latest/nix/unistd/fn.tcsetpgrp.html, which is a safe function.
-        unsafe {
-            libc::tcsetpgrp(libc::STDIN_FILENO, process.id() as i32);
-        }
+// On unix, if `prepare_to_foreground` function is not called,
+// the function will fail with silence and do nothing.
+//
+// The function does nothing on windows.
+fn set_foreground(process: &std::process::Child) {
+    // it's ok to use unsafe here
+    // the implementaion here is just the same as
+    // https://docs.rs/nix/latest/nix/unistd/fn.tcsetpgrp.html, which is a safe function.
+    #[cfg(target_family = "unix")]
+    unsafe {
+        libc::tcsetpgrp(libc::STDIN_FILENO, process.id() as i32);
     }
+}
 
-    /// Reset foreground to current process, and reset back `SIGTTOU`, `SIGTTIN` single handler.
-    ///
-    /// ## Safety
-    /// It can only be called when you have called `set_foreground`, or results in undefined behavior.
-    pub unsafe fn reset_foreground_id() {
+/// Reset foreground to current process, and reset back `SIGTTOU`, `SIGTTIN` single handler.
+///
+/// ## Safety
+/// On unix, it can only be called when you have called `set_foreground`, or results in undefined behavior.
+///
+/// The function does nothing on windows.
+unsafe fn reset_foreground_id() {
+    #[cfg(target_family = "unix")]
+    {
         libc::tcsetpgrp(libc::STDIN_FILENO, libc::getpgrp());
         libc::signal(libc::SIGTTOU, libc::SIG_DFL);
         libc::signal(libc::SIGTTIN, libc::SIG_DFL);
     }
 }
-
-// TODO: investigate if we can set foreground process through windows system call.
-#[cfg(target_family = "windows")]
-mod fg_process_setup {
-
-    pub fn prepare_to_foreground(_external_command: &mut std::process::Command) {}
-
-    pub fn set_foreground(_process: &std::process::Child) {}
-
-    pub unsafe fn reset_foreground_id() {}
-}