diff --git a/src/commands/mount.rs b/src/commands/mount.rs
index 71bc2bd4..0959bdcf 100644
--- a/src/commands/mount.rs
+++ b/src/commands/mount.rs
@@ -1,6 +1,7 @@
 use std::{
-    ffi::CString,
+    ffi::{CString, OsString},
     io::{stdout, IsTerminal},
+    os::unix::ffi::OsStringExt,
     path::{Path, PathBuf},
     ptr, str,
 };
@@ -17,14 +18,14 @@ use crate::{
 };
 
 fn mount_inner(
-    src: String,
+    src: OsString,
     target: &std::path::Path,
     fstype: &str,
     mut mountflags: libc::c_ulong,
     data: Option<String>,
 ) -> anyhow::Result<()> {
     // bind the CStrings to keep them alive
-    let c_src = CString::new(src.clone())?;
+    let c_src = CString::new(src.clone().into_vec())?;
     let c_target = path_to_cstr(target);
     let data = data.map(CString::new).transpose()?;
     let fstype = CString::new(fstype)?;
@@ -63,9 +64,9 @@ fn mount_inner(
         let e = crate::ErrnoError(err);
 
         if err.0 == libc::EBUSY {
-            eprintln!("mount: {}: {} already mounted or mount point busy", target.to_string_lossy(), src);
+            eprintln!("mount: {}: {:?} already mounted or mount point busy", target.to_string_lossy(), src);
         } else {
-            eprintln!("mount: {}: {}", src, e);
+            eprintln!("mount: {:?}: {}", src, e);
         }
 
         Err(e.into())
@@ -160,7 +161,7 @@ fn cmd_mount_inner(cli: &Cli) -> Result<()> {
 
     if let Some(mountpoint) = cli.mountpoint.as_deref() {
         info!(
-            "mounting with params: device: {}, target: {}, options: {}",
+            "mounting with params: device: {:?}, target: {}, options: {}",
             devices,
             mountpoint.to_string_lossy(),
             &cli.options
@@ -169,7 +170,7 @@ fn cmd_mount_inner(cli: &Cli) -> Result<()> {
         mount_inner(devices, mountpoint, "bcachefs", mountflags, optstr)
     } else {
         info!(
-            "would mount with params: device: {}, options: {}",
+            "would mount with params: device: {:?}, options: {}",
             devices, &cli.options
         );
 
diff --git a/src/device_scan.rs b/src/device_scan.rs
index cb153198..479ebd20 100644
--- a/src/device_scan.rs
+++ b/src/device_scan.rs
@@ -1,8 +1,9 @@
 use std::{
-    ffi::{CStr, CString, c_char, c_int},
+    ffi::{CStr, CString, c_char, c_int, OsString, OsStr},
     collections::HashMap,
     env,
     fs,
+    os::unix::ffi::OsStringExt,
     path::{Path, PathBuf},
     str,
 };
@@ -179,14 +180,14 @@ pub fn scan_sbs(device: &String, opts: &bch_opts) -> Result<Vec<(PathBuf, bch_sb
     }
 }
 
-pub fn joined_device_str(sbs: &Vec<(PathBuf, bch_sb_handle)>) -> String {
+pub fn joined_device_str(sbs: &Vec<(PathBuf, bch_sb_handle)>) -> OsString {
     sbs.iter()
-        .map(|sb| sb.0.clone().into_os_string().into_string().unwrap())
+        .map(|sb| sb.0.clone().into_os_string())
         .collect::<Vec<_>>()
-        .join(":")
+        .join(OsStr::new(":"))
 }
 
-pub fn scan_devices(device: &String, opts: &bch_opts) -> Result<String> {
+pub fn scan_devices(device: &String, opts: &bch_opts) -> Result<OsString> {
     let mut sbs = scan_sbs(device, opts)?;
 
     for sb in &mut sbs {
@@ -236,8 +237,10 @@ pub extern "C" fn bch2_scan_devices(device: *const c_char) -> *mut c_char {
     // how to initialize to default/empty?
     let opts = bch_bindgen::opts::parse_mount_opts(None, None, true).unwrap_or_default();
 
-    CString::new(scan_devices(&device, &opts).unwrap_or_else(|e| {
+    let devs = scan_devices(&device, &opts).unwrap_or_else(|e| {
         eprintln!("bcachefs ({}): error reading superblock: {}", device, e);
         std::process::exit(-1);
-    })).unwrap().into_raw()
+    });
+
+    CString::new(devs.into_vec()).unwrap().into_raw()
 }