diff --git a/src/tools/run-make-support/src/external_deps/cc.rs b/src/tools/run-make-support/src/external_deps/cc.rs
index 677790b0aa9..840bfa0d2b4 100644
--- a/src/tools/run-make-support/src/external_deps/cc.rs
+++ b/src/tools/run-make-support/src/external_deps/cc.rs
@@ -1,7 +1,10 @@
 use std::path::Path;
 
 use crate::command::Command;
-use crate::{cygpath_windows, env_var, is_msvc, is_windows, uname};
+use crate::{env_var, is_msvc, is_windows, uname};
+
+// FIXME(jieyouxu): can we get rid of the `cygpath` external dependency?
+use super::cygpath::get_windows_path;
 
 /// Construct a new platform-specific C compiler invocation.
 ///
@@ -72,10 +75,10 @@ pub fn out_exe(&mut self, name: &str) -> &mut Self {
 
         if is_msvc() {
             path.set_extension("exe");
-            let fe_path = cygpath_windows(&path);
+            let fe_path = get_windows_path(&path);
             path.set_extension("");
             path.set_extension("obj");
-            let fo_path = cygpath_windows(path);
+            let fo_path = get_windows_path(path);
             self.cmd.arg(format!("-Fe:{fe_path}"));
             self.cmd.arg(format!("-Fo:{fo_path}"));
         } else {
diff --git a/src/tools/run-make-support/src/external_deps/cygpath.rs b/src/tools/run-make-support/src/external_deps/cygpath.rs
new file mode 100644
index 00000000000..07d8e840a63
--- /dev/null
+++ b/src/tools/run-make-support/src/external_deps/cygpath.rs
@@ -0,0 +1,35 @@
+use std::panic;
+use std::path::Path;
+
+use crate::command::Command;
+use crate::util::handle_failed_output;
+
+/// Use `cygpath -w` on a path to get a Windows path string back. This assumes that `cygpath` is
+/// available on the platform!
+///
+/// # FIXME
+///
+/// FIXME(jieyouxu): we should consider not depending on `cygpath`.
+///
+/// > The cygpath program is a utility that converts Windows native filenames to Cygwin POSIX-style
+/// > pathnames and vice versa.
+/// >
+/// > [irrelevant entries omitted...]
+/// >
+/// > `-w, --windows         print Windows form of NAMEs (C:\WINNT)`
+/// >
+/// > -- *from [cygpath documentation](https://cygwin.com/cygwin-ug-net/cygpath.html)*.
+#[track_caller]
+#[must_use]
+pub fn get_windows_path<P: AsRef<Path>>(path: P) -> String {
+    let caller = panic::Location::caller();
+    let mut cygpath = Command::new("cygpath");
+    cygpath.arg("-w");
+    cygpath.arg(path.as_ref());
+    let output = cygpath.run();
+    if !output.status().success() {
+        handle_failed_output(&cygpath, output, caller.line());
+    }
+    // cygpath -w can attach a newline
+    output.stdout_utf8().trim().to_string()
+}
diff --git a/src/tools/run-make-support/src/external_deps/mod.rs b/src/tools/run-make-support/src/external_deps/mod.rs
index 13020b51563..a2dc426f3f2 100644
--- a/src/tools/run-make-support/src/external_deps/mod.rs
+++ b/src/tools/run-make-support/src/external_deps/mod.rs
@@ -1,10 +1,5 @@
 //! This module contains external tool dependencies that we assume are available in the environment,
 //! such as `cc` or `python`.
-//!
-//! # Notes
-//!
-//! - This is not the *only* place where external dependencies are assumed or referenced. For
-//!   example, see [`cygpath_windows`][crate::path_helpers::cygpath_windows].
 
 pub mod c_build;
 pub mod cc;
@@ -14,3 +9,6 @@
 pub mod python;
 pub mod rustc;
 pub mod rustdoc;
+
+// Library-internal external dependency.
+mod cygpath;
diff --git a/src/tools/run-make-support/src/lib.rs b/src/tools/run-make-support/src/lib.rs
index 38070f79edc..5416a6920a5 100644
--- a/src/tools/run-make-support/src/lib.rs
+++ b/src/tools/run-make-support/src/lib.rs
@@ -62,7 +62,7 @@
 };
 
 /// Path-related helpers.
-pub use path_helpers::{cwd, cygpath_windows, path, source_root};
+pub use path_helpers::{cwd, path, source_root};
 
 /// Helpers for common fs operations.
 pub use fs_helpers::{copy_dir_all, create_symlink, read_dir};
diff --git a/src/tools/run-make-support/src/path_helpers.rs b/src/tools/run-make-support/src/path_helpers.rs
index f46368b53f8..b29d8727d2b 100644
--- a/src/tools/run-make-support/src/path_helpers.rs
+++ b/src/tools/run-make-support/src/path_helpers.rs
@@ -1,11 +1,8 @@
 //! Collection of path-related helpers.
 
-use std::panic;
 use std::path::{Path, PathBuf};
 
-use crate::command::Command;
 use crate::env::env_var;
-use crate::util::handle_failed_output;
 
 /// Return the current working directory.
 ///
@@ -34,33 +31,3 @@ pub fn path<P: AsRef<Path>>(p: P) -> PathBuf {
 pub fn source_root() -> PathBuf {
     env_var("SOURCE_ROOT").into()
 }
-
-/// Use `cygpath -w` on a path to get a Windows path string back. This assumes that `cygpath` is
-/// available on the platform!
-///
-/// # FIXME
-///
-/// FIXME(jieyouxu): we should consider not depending on `cygpath`.
-///
-/// > The cygpath program is a utility that converts Windows native filenames to Cygwin POSIX-style
-/// > pathnames and vice versa.
-/// >
-/// > [irrelevant entries omitted...]
-/// >
-/// > `-w, --windows         print Windows form of NAMEs (C:\WINNT)`
-/// >
-/// > -- *from [cygpath documentation](https://cygwin.com/cygwin-ug-net/cygpath.html)*.
-#[track_caller]
-#[must_use]
-pub fn cygpath_windows<P: AsRef<Path>>(path: P) -> String {
-    let caller = panic::Location::caller();
-    let mut cygpath = Command::new("cygpath");
-    cygpath.arg("-w");
-    cygpath.arg(path.as_ref());
-    let output = cygpath.run();
-    if !output.status().success() {
-        handle_failed_output(&cygpath, output, caller.line());
-    }
-    // cygpath -w can attach a newline
-    output.stdout_utf8().trim().to_string()
-}