diff --git a/core/io/unix.rs b/core/io/unix.rs
index c07285bc9..1526e13e4 100644
--- a/core/io/unix.rs
+++ b/core/io/unix.rs
@@ -13,6 +13,7 @@ use rustix::{
 use std::{
     cell::{RefCell, UnsafeCell},
     mem::MaybeUninit,
+    sync::Mutex,
 };
 
 use std::{io::ErrorKind, sync::Arc};
@@ -227,7 +228,7 @@ impl IO for UnixIO {
 
         #[allow(clippy::arc_with_non_send_sync)]
         let unix_file = Arc::new(UnixFile {
-            file: Arc::new(RefCell::new(file)),
+            file: Arc::new(Mutex::new(file)),
             poller: BorrowedPollHandler(self.poller.as_mut().into()),
             callbacks: BorrowedCallbacks(self.callbacks.as_mut().into()),
         });
@@ -250,13 +251,13 @@ impl IO for UnixIO {
             if let Some(cf) = self.callbacks.get(event.key) {
                 let result = match cf {
                     CompletionCallback::Read(ref file, ref c, pos) => {
-                        let file = file.borrow_mut();
+                        let file = file.lock().unwrap();
                         let r = c.as_read();
                         let mut buf = r.buf_mut();
                         rustix::io::pread(file.as_fd(), buf.as_mut_slice(), *pos as u64)
                     }
                     CompletionCallback::Write(ref file, _, ref buf, pos) => {
-                        let file = file.borrow_mut();
+                        let file = file.lock().unwrap();
                         let buf = buf.borrow();
                         rustix::io::pwrite(file.as_fd(), buf.as_slice(), *pos as u64)
                     }
@@ -304,9 +305,9 @@ impl IO for UnixIO {
 }
 
 enum CompletionCallback {
-    Read(Arc<RefCell<std::fs::File>>, Arc<Completion>, usize),
+    Read(Arc<Mutex<std::fs::File>>, Arc<Completion>, usize),
     Write(
-        Arc<RefCell<std::fs::File>>,
+        Arc<Mutex<std::fs::File>>,
         Arc<Completion>,
         Arc<RefCell<crate::Buffer>>,
         usize,
@@ -315,7 +316,7 @@ enum CompletionCallback {
 
 pub struct UnixFile<'io> {
     #[allow(clippy::arc_with_non_send_sync)]
-    file: Arc<RefCell<std::fs::File>>,
+    file: Arc<Mutex<std::fs::File>>,
     poller: BorrowedPollHandler<'io>,
     callbacks: BorrowedCallbacks<'io>,
 }
@@ -324,7 +325,7 @@ unsafe impl Sync for UnixFile<'_> {}
 
 impl File for UnixFile<'_> {
     fn lock_file(&self, exclusive: bool) -> Result<()> {
-        let fd = self.file.borrow();
+        let fd = self.file.lock().unwrap();
         let fd = fd.as_fd();
         // F_SETLK is a non-blocking lock. The lock will be released when the file is closed
         // or the process exits or after an explicit unlock.
@@ -351,7 +352,7 @@ impl File for UnixFile<'_> {
     }
 
     fn unlock_file(&self) -> Result<()> {
-        let fd = self.file.borrow();
+        let fd = self.file.lock().unwrap();
         let fd = fd.as_fd();
         fs::fcntl_lock(fd, FlockOperation::NonBlockingUnlock).map_err(|e| {
             LimboError::LockingError(format!(
@@ -364,7 +365,7 @@ impl File for UnixFile<'_> {
 
     #[instrument(err, skip_all, level = Level::TRACE)]
     fn pread(&self, pos: usize, c: Arc<Completion>) -> Result<Arc<Completion>> {
-        let file = self.file.borrow();
+        let file = self.file.lock().unwrap();
         let result = {
             let r = c.as_read();
             let mut buf = r.buf_mut();
@@ -402,7 +403,7 @@ impl File for UnixFile<'_> {
         buffer: Arc<RefCell<crate::Buffer>>,
         c: Arc<Completion>,
     ) -> Result<Arc<Completion>> {
-        let file = self.file.borrow();
+        let file = self.file.lock().unwrap();
         let result = {
             let buf = buffer.borrow();
             rustix::io::pwrite(file.as_fd(), buf.as_slice(), pos as u64)
@@ -432,7 +433,7 @@ impl File for UnixFile<'_> {
 
     #[instrument(err, skip_all, level = Level::TRACE)]
     fn sync(&self, c: Arc<Completion>) -> Result<Arc<Completion>> {
-        let file = self.file.borrow();
+        let file = self.file.lock().unwrap();
         let result = fs::fsync(file.as_fd());
         match result {
             Ok(()) => {
@@ -446,7 +447,7 @@ impl File for UnixFile<'_> {
 
     #[instrument(err, skip_all, level = Level::TRACE)]
     fn size(&self) -> Result<u64> {
-        let file = self.file.borrow();
+        let file = self.file.lock().unwrap();
         Ok(file.metadata()?.len())
     }
 }