diff --git a/src/cli/self_update.rs b/src/cli/self_update.rs
index 63730eb7e2..5ae746416c 100644
--- a/src/cli/self_update.rs
+++ b/src/cli/self_update.rs
@@ -238,6 +238,7 @@ pub fn install(no_prompt: bool, verbose: bool, quiet: bool, mut opts: InstallOpt
     do_pre_install_sanity_checks()?;
     do_pre_install_options_sanity_checks(&opts)?;
     check_existence_of_rustc_or_cargo_in_path(no_prompt)?;
+    #[cfg(unix)]
     do_anti_sudo_check(no_prompt)?;
 
     let mut term = term2::stdout();
@@ -467,63 +468,33 @@ fn do_pre_install_options_sanity_checks(opts: &InstallOpts) -> Result<()> {
 // If the user is trying to install with sudo, on some systems this will
 // result in writing root-owned files to the user's home directory, because
 // sudo is configured not to change $HOME. Don't let that bogosity happen.
-#[allow(dead_code)]
+#[cfg(unix)]
 fn do_anti_sudo_check(no_prompt: bool) -> Result<()> {
-    use std::ffi::OsString;
-
-    #[cfg(unix)]
-    pub fn home_mismatch() -> (bool, OsString, String) {
-        use std::ffi::CStr;
-        use std::mem::MaybeUninit;
-        use std::ptr;
-
+    pub fn home_mismatch() -> (bool, PathBuf, PathBuf) {
+        let fallback = || (false, PathBuf::new(), PathBuf::new());
         // test runner should set this, nothing else
-        if let Ok(true) = env::var("RUSTUP_INIT_SKIP_SUDO_CHECK").map(|s| s == "yes") {
-            return (false, OsString::new(), String::new());
-        }
-        let mut buf = [0u8; 1024];
-        let mut pwd = MaybeUninit::<libc::passwd>::uninit();
-        let mut pwdp: *mut libc::passwd = ptr::null_mut();
-        let rv = unsafe {
-            libc::getpwuid_r(
-                libc::geteuid(),
-                pwd.as_mut_ptr(),
-                buf.as_mut_ptr().cast::<libc::c_char>(),
-                buf.len(),
-                (&mut pwdp) as *mut *mut libc::passwd,
-            )
-        };
-        if rv != 0 || pwdp.is_null() {
-            warn!("getpwuid_r: couldn't get user data");
-            return (false, OsString::new(), String::new());
+        if env::var_os("RUSTUP_INIT_SKIP_SUDO_CHECK").map_or(false, |s| s == "yes") {
+            return fallback();
         }
-        let pwd = unsafe { pwd.assume_init() };
-        let pw_dir = unsafe { CStr::from_ptr(pwd.pw_dir) }.to_str().ok();
-        let env_home = env::var_os("HOME");
-        match (env_home, pw_dir) {
-            (None, _) | (_, None) => (false, OsString::new(), String::new()),
-            (Some(eh), Some(pd)) => (eh != pd, eh, String::from(pd)),
-        }
-    }
 
-    #[cfg(not(unix))]
-    pub fn home_mismatch() -> (bool, OsString, String) {
-        (false, OsString::new(), String::new())
+        match (utils::home_dir_from_passwd(), env::var_os("HOME")) {
+            (Some(pw), Some(eh)) if eh != pw => return (true, PathBuf::from(eh), pw),
+            (None, _) => warn!("getpwuid_r: couldn't get user data"),
+            _ => {}
+        }
+        fallback()
     }
 
-    match (home_mismatch(), no_prompt) {
-        ((false, _, _), _) => (),
-        ((true, env_home, euid_home), false) => {
+    match home_mismatch() {
+        (false, _, _) => {}
+        (true, env_home, euid_home) => {
             err!("$HOME differs from euid-obtained home directory: you may be using sudo");
-            err!("$HOME directory: {:?}", env_home);
-            err!("euid-obtained home directory: {}", euid_home);
-            err!("if this is what you want, restart the installation with `-y'");
-            process::exit(1);
-        }
-        ((true, env_home, euid_home), true) => {
-            warn!("$HOME differs from euid-obtained home directory: you may be using sudo");
-            warn!("$HOME directory: {:?}", env_home);
-            warn!("euid-obtained home directory: {}", euid_home);
+            err!("$HOME directory: {}", env_home.display());
+            err!("euid-obtained home directory: {}", euid_home.display());
+            if !no_prompt {
+                err!("if this is what you want, restart the installation with `-y'");
+                process::exit(1);
+            }
         }
     }
 
diff --git a/src/utils/utils.rs b/src/utils/utils.rs
index b920f6e99b..14330f99c9 100644
--- a/src/utils/utils.rs
+++ b/src/utils/utils.rs
@@ -670,6 +670,39 @@ impl<'a> io::Read for FileReaderWithProgress<'a> {
     }
 }
 
+// search user database to get home dir of euid user
+#[cfg(unix)]
+pub fn home_dir_from_passwd() -> Option<PathBuf> {
+    use std::ffi::CStr;
+    use std::mem::MaybeUninit;
+    use std::os::unix::ffi::OsStringExt;
+    use std::ptr;
+    unsafe {
+        let init_size = match libc::sysconf(libc::_SC_GETPW_R_SIZE_MAX) {
+            -1 => 1024,
+            n => n as usize,
+        };
+        let mut buf = Vec::with_capacity(init_size);
+        let mut pwd: MaybeUninit<libc::passwd> = MaybeUninit::uninit();
+        let mut pwdp = ptr::null_mut();
+        match libc::getpwuid_r(
+            libc::geteuid(),
+            pwd.as_mut_ptr(),
+            buf.as_mut_ptr(),
+            buf.capacity(),
+            &mut pwdp,
+        ) {
+            0 if !pwdp.is_null() => {
+                let pwd = pwd.assume_init();
+                let bytes = CStr::from_ptr(pwd.pw_dir).to_bytes().to_vec();
+                let pw_dir = OsString::from_vec(bytes);
+                Some(PathBuf::from(pw_dir))
+            }
+            _ => None,
+        }
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;