diff --git a/src/isolate.rs b/src/isolate.rs
index 3379eb80d0b8ae97270619d311234d88c7e21bfa..6b2814ec4c06a3862ad48c927a1913e6c5ace424 100644
--- a/src/isolate.rs
+++ b/src/isolate.rs
@@ -14,6 +14,7 @@ use permissions::DenoPermissions;
 use futures::Future;
 use libc::c_void;
 use std;
+use std::cell::Cell;
 use std::env;
 use std::ffi::CStr;
 use std::ffi::CString;
@@ -38,19 +39,17 @@ pub type Buf = Box<[u8]>;
 pub type Op = Future<Item = Buf, Error = DenoError> + Send;
 
 // Returns (is_sync, op)
-pub type Dispatch = fn(
-  isolate: &mut Isolate,
-  buf: libdeno::deno_buf,
-  data_buf: libdeno::deno_buf,
-) -> (bool, Box<Op>);
+pub type Dispatch =
+  fn(isolate: &Isolate, buf: libdeno::deno_buf, data_buf: libdeno::deno_buf)
+    -> (bool, Box<Op>);
 
 pub struct Isolate {
   libdeno_isolate: *const libdeno::isolate,
   dispatch: Dispatch,
   rx: mpsc::Receiver<(i32, Buf)>,
   tx: mpsc::Sender<(i32, Buf)>,
-  ntasks: i32,
-  pub timeout_due: Option<Instant>,
+  ntasks: Cell<i32>,
+  timeout_due: Cell<Option<Instant>>,
   pub state: Arc<IsolateState>,
 }
 
@@ -79,18 +78,22 @@ impl IsolateState {
     }
   }
 
+  #[inline]
   pub fn check_write(&self, filename: &str) -> DenoResult<()> {
     self.permissions.check_write(filename)
   }
 
+  #[inline]
   pub fn check_env(&self) -> DenoResult<()> {
     self.permissions.check_env()
   }
 
+  #[inline]
   pub fn check_net(&self, filename: &str) -> DenoResult<()> {
     self.permissions.check_net(filename)
   }
 
+  #[inline]
   pub fn check_run(&self) -> DenoResult<()> {
     self.permissions.check_run()
   }
@@ -154,23 +157,35 @@ impl Isolate {
       dispatch,
       rx,
       tx,
-      ntasks: 0,
-      timeout_due: None,
+      ntasks: Cell::new(0),
+      timeout_due: Cell::new(None),
       state,
     }
   }
 
-  pub fn as_void_ptr(&mut self) -> *mut c_void {
-    self as *mut _ as *mut c_void
+  #[inline]
+  pub fn as_raw_ptr(&self) -> *const c_void {
+    self as *const _ as *const c_void
+  }
+
+  #[inline]
+  pub unsafe fn from_raw_ptr<'a>(ptr: *const c_void) -> &'a Self {
+    let ptr = ptr as *const _;
+    &*ptr
   }
 
-  pub fn from_void_ptr<'a>(ptr: *mut c_void) -> &'a mut Self {
-    let ptr = ptr as *mut _;
-    unsafe { &mut *ptr }
+  #[inline]
+  pub fn get_timeout_due(&self) -> Option<Instant> {
+    self.timeout_due.clone().into_inner()
+  }
+
+  #[inline]
+  pub fn set_timeout_due(&self, inst: Option<Instant>) {
+    self.timeout_due.set(inst);
   }
 
   pub fn execute(
-    &mut self,
+    &self,
     js_filename: &str,
     js_source: &str,
   ) -> Result<(), DenoException> {
@@ -179,7 +194,7 @@ impl Isolate {
     let r = unsafe {
       libdeno::deno_execute(
         self.libdeno_isolate,
-        self.as_void_ptr(),
+        self.as_raw_ptr(),
         filename.as_ptr(),
         source.as_ptr(),
       )
@@ -192,21 +207,21 @@ impl Isolate {
     Ok(())
   }
 
-  pub fn respond(&mut self, req_id: i32, buf: Buf) {
+  pub fn respond(&self, req_id: i32, buf: Buf) {
     self.state.metrics_op_completed(buf.len());
     // deno_respond will memcpy the buf into V8's heap,
     // so borrowing a reference here is sufficient.
     unsafe {
       libdeno::deno_respond(
         self.libdeno_isolate,
-        self.as_void_ptr(),
+        self.as_raw_ptr(),
         req_id,
         buf.as_ref().into(),
       )
     }
   }
 
-  fn complete_op(&mut self, req_id: i32, buf: Buf) {
+  fn complete_op(&self, req_id: i32, buf: Buf) {
     // Receiving a message on rx exactly corresponds to an async task
     // completing.
     self.ntasks_decrement();
@@ -214,12 +229,12 @@ impl Isolate {
     self.respond(req_id, buf);
   }
 
-  fn timeout(&mut self) {
+  fn timeout(&self) {
     let dummy_buf = libdeno::deno_buf::empty();
     unsafe {
       libdeno::deno_respond(
         self.libdeno_isolate,
-        self.as_void_ptr(),
+        self.as_raw_ptr(),
         -1,
         dummy_buf,
       )
@@ -234,10 +249,10 @@ impl Isolate {
 
   // TODO Use Park abstraction? Note at time of writing Tokio default runtime
   // does not have new_with_park().
-  pub fn event_loop(&mut self) {
+  pub fn event_loop(&self) {
     // Main thread event loop.
     while !self.is_idle() {
-      match recv_deadline(&self.rx, self.timeout_due) {
+      match recv_deadline(&self.rx, self.get_timeout_due()) {
         Ok((req_id, buf)) => self.complete_op(req_id, buf),
         Err(mpsc::RecvTimeoutError::Timeout) => self.timeout(),
         Err(e) => panic!("recv_deadline() failed: {:?}", e),
@@ -248,18 +263,21 @@ impl Isolate {
     self.check_promise_errors();
   }
 
-  fn ntasks_increment(&mut self) {
-    assert!(self.ntasks >= 0);
-    self.ntasks += 1;
+  #[inline]
+  fn ntasks_increment(&self) {
+    assert!(self.ntasks.get() >= 0);
+    self.ntasks.set(self.ntasks.get() + 1);
   }
 
-  fn ntasks_decrement(&mut self) {
-    self.ntasks -= 1;
-    assert!(self.ntasks >= 0);
+  #[inline]
+  fn ntasks_decrement(&self) {
+    self.ntasks.set(self.ntasks.get() - 1);
+    assert!(self.ntasks.get() >= 0);
   }
 
+  #[inline]
   fn is_idle(&self) -> bool {
-    self.ntasks == 0 && self.timeout_due.is_none()
+    self.ntasks.get() == 0 && self.get_timeout_due().is_none()
   }
 }
 
@@ -280,7 +298,9 @@ extern "C" fn pre_dispatch(
   let bytes_sent_control = control_buf.len();
   let bytes_sent_data = data_buf.len();
 
-  let isolate = Isolate::from_void_ptr(user_data);
+  // We should ensure that there is no other `&mut Isolate` exists.
+  // And also, it should be in the same thread with other `&Isolate`s.
+  let isolate = unsafe { Isolate::from_raw_ptr(user_data) };
   let dispatch = isolate.dispatch;
   let (is_sync, op) = dispatch(isolate, control_buf, data_buf);
 
@@ -353,7 +373,7 @@ mod tests {
 
     let state = Arc::new(IsolateState::new(flags, rest_argv));
     let snapshot = libdeno::deno_buf::empty();
-    let mut isolate = Isolate::new(snapshot, state, dispatch_sync);
+    let isolate = Isolate::new(snapshot, state, dispatch_sync);
     tokio_util::init(|| {
       isolate
         .execute(
@@ -374,7 +394,7 @@ mod tests {
   }
 
   fn dispatch_sync(
-    _isolate: &mut Isolate,
+    _isolate: &Isolate,
     control: libdeno::deno_buf,
     data: libdeno::deno_buf,
   ) -> (bool, Box<Op>) {
@@ -395,7 +415,7 @@ mod tests {
     let (flags, rest_argv, _) = flags::set_flags(argv).unwrap();
     let state = Arc::new(IsolateState::new(flags, rest_argv));
     let snapshot = libdeno::deno_buf::empty();
-    let mut isolate = Isolate::new(snapshot, state, metrics_dispatch_sync);
+    let isolate = Isolate::new(snapshot, state, metrics_dispatch_sync);
     tokio_util::init(|| {
       // Verify that metrics have been properly initialized.
       {
@@ -432,7 +452,7 @@ mod tests {
     let (flags, rest_argv, _) = flags::set_flags(argv).unwrap();
     let state = Arc::new(IsolateState::new(flags, rest_argv));
     let snapshot = libdeno::deno_buf::empty();
-    let mut isolate = Isolate::new(snapshot, state, metrics_dispatch_async);
+    let isolate = Isolate::new(snapshot, state, metrics_dispatch_async);
     tokio_util::init(|| {
       // Verify that metrics have been properly initialized.
       {
@@ -481,7 +501,7 @@ mod tests {
   }
 
   fn metrics_dispatch_sync(
-    _isolate: &mut Isolate,
+    _isolate: &Isolate,
     _control: libdeno::deno_buf,
     _data: libdeno::deno_buf,
   ) -> (bool, Box<Op>) {
@@ -492,7 +512,7 @@ mod tests {
   }
 
   fn metrics_dispatch_async(
-    _isolate: &mut Isolate,
+    _isolate: &Isolate,
     _control: libdeno::deno_buf,
     _data: libdeno::deno_buf,
   ) -> (bool, Box<Op>) {
diff --git a/src/libdeno.rs b/src/libdeno.rs
index 3e41c7d6059ace53c4e2fc12f76a65aacce9c7ab..cbc074f1be87ba663752dfbabcc91551e42a9406 100644
--- a/src/libdeno.rs
+++ b/src/libdeno.rs
@@ -31,6 +31,7 @@ pub struct deno_buf {
 unsafe impl Send for deno_buf {}
 
 impl deno_buf {
+  #[inline]
   pub fn empty() -> Self {
     Self {
       alloc_ptr: null(),
@@ -40,6 +41,7 @@ impl deno_buf {
     }
   }
 
+  #[inline]
   pub unsafe fn from_raw_parts(ptr: *const u8, len: usize) -> Self {
     Self {
       alloc_ptr: null(),
@@ -52,6 +54,7 @@ impl deno_buf {
 
 /// Converts Rust &Buf to libdeno `deno_buf`.
 impl<'a> From<&'a [u8]> for deno_buf {
+  #[inline]
   fn from(x: &'a [u8]) -> Self {
     Self {
       alloc_ptr: null(),
@@ -64,27 +67,37 @@ impl<'a> From<&'a [u8]> for deno_buf {
 
 impl Deref for deno_buf {
   type Target = [u8];
+  #[inline]
   fn deref(&self) -> &[u8] {
     unsafe { std::slice::from_raw_parts(self.data_ptr, self.data_len) }
   }
 }
 
 impl DerefMut for deno_buf {
+  #[inline]
   fn deref_mut(&mut self) -> &mut [u8] {
     unsafe {
+      if self.alloc_ptr.is_null() {
+        panic!("Can't modify the buf");
+      }
       std::slice::from_raw_parts_mut(self.data_ptr as *mut u8, self.data_len)
     }
   }
 }
 
 impl AsRef<[u8]> for deno_buf {
+  #[inline]
   fn as_ref(&self) -> &[u8] {
     &*self
   }
 }
 
 impl AsMut<[u8]> for deno_buf {
+  #[inline]
   fn as_mut(&mut self) -> &mut [u8] {
+    if self.alloc_ptr.is_null() {
+      panic!("Can't modify the buf");
+    }
     &mut *self
   }
 }
@@ -112,13 +125,13 @@ extern "C" {
   pub fn deno_check_promise_errors(i: *const isolate);
   pub fn deno_respond(
     i: *const isolate,
-    user_data: *mut c_void,
+    user_data: *const c_void,
     req_id: i32,
     buf: deno_buf,
   );
   pub fn deno_execute(
     i: *const isolate,
-    user_data: *mut c_void,
+    user_data: *const c_void,
     js_filename: *const c_char,
     js_source: *const c_char,
   ) -> c_int;
diff --git a/src/main.rs b/src/main.rs
index 1224d2af2084551e34b250a8beffe4de8315d170..f2e241ab16982b8b4aef655e30db6e942394f695 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -98,7 +98,7 @@ fn main() {
 
   let state = Arc::new(isolate::IsolateState::new(flags, rest_argv));
   let snapshot = snapshot::deno_snapshot();
-  let mut isolate = isolate::Isolate::new(snapshot, state, ops::dispatch);
+  let isolate = isolate::Isolate::new(snapshot, state, ops::dispatch);
   tokio_util::init(|| {
     isolate
       .execute("deno_main.js", "denoMain();")
diff --git a/src/ops.rs b/src/ops.rs
index 908de1e230894208ba38656f274832669b149894..7c4fc5119f9e7f35c0370ffc65d7bbe5352fd0f8 100644
--- a/src/ops.rs
+++ b/src/ops.rs
@@ -35,7 +35,6 @@ use std::path::Path;
 use std::path::PathBuf;
 use std::process::Command;
 use std::str::FromStr;
-use std::sync::Arc;
 use std::time::UNIX_EPOCH;
 use std::time::{Duration, Instant};
 use tokio;
@@ -49,10 +48,10 @@ type OpResult = DenoResult<Buf>;
 // TODO Ideally we wouldn't have to box the Op being returned.
 // The box is just to make it easier to get a prototype refactor working.
 type OpCreator =
-  fn(state: &Arc<IsolateState>, base: &msg::Base, data: libdeno::deno_buf)
+  fn(state: &IsolateState, base: &msg::Base, data: libdeno::deno_buf)
     -> Box<Op>;
 
-// Hopefully Rust optimizes this away.
+#[inline]
 fn empty_buf() -> Buf {
   Box::new([])
 }
@@ -62,7 +61,7 @@ fn empty_buf() -> Buf {
 /// control corresponds to the first argument of libdeno.send().
 /// data corresponds to the second argument of libdeno.send().
 pub fn dispatch(
-  isolate: &mut Isolate,
+  isolate: &Isolate,
   control: libdeno::deno_buf,
   data: libdeno::deno_buf,
 ) -> (bool, Box<Op>) {
@@ -121,7 +120,7 @@ pub fn dispatch(
         msg::enum_name_any(inner_type)
       )),
     };
-    op_creator(&isolate.state.clone(), &base, data)
+    op_creator(&isolate.state, &base, data)
   };
 
   let boxed_op = Box::new(
@@ -169,7 +168,7 @@ pub fn dispatch(
 }
 
 fn op_exit(
-  _config: &Arc<IsolateState>,
+  _config: &IsolateState,
   base: &msg::Base,
   _data: libdeno::deno_buf,
 ) -> Box<Op> {
@@ -178,7 +177,7 @@ fn op_exit(
 }
 
 fn op_start(
-  state: &Arc<IsolateState>,
+  state: &IsolateState,
   base: &msg::Base,
   data: libdeno::deno_buf,
 ) -> Box<Op> {
@@ -234,8 +233,7 @@ fn serialize_response(
   msg::finish_base_buffer(builder, base);
   let data = builder.finished_data();
   // println!("serialize_response {:x?}", data);
-  let vec = data.to_vec();
-  vec.into_boxed_slice()
+  data.into()
 }
 
 fn ok_future(buf: Buf) -> Box<Op> {
@@ -249,7 +247,7 @@ fn odd_future(err: DenoError) -> Box<Op> {
 
 // https://github.com/denoland/deno/blob/golang/os.go#L100-L154
 fn op_code_fetch(
-  state: &Arc<IsolateState>,
+  state: &IsolateState,
   base: &msg::Base,
   data: libdeno::deno_buf,
 ) -> Box<Op> {
@@ -292,7 +290,7 @@ fn op_code_fetch(
 
 // https://github.com/denoland/deno/blob/golang/os.go#L156-L169
 fn op_code_cache(
-  state: &Arc<IsolateState>,
+  state: &IsolateState,
   base: &msg::Base,
   data: libdeno::deno_buf,
 ) -> Box<Op> {
@@ -311,7 +309,7 @@ fn op_code_cache(
 }
 
 fn op_chdir(
-  _state: &Arc<IsolateState>,
+  _state: &IsolateState,
   base: &msg::Base,
   data: libdeno::deno_buf,
 ) -> Box<Op> {
@@ -325,7 +323,7 @@ fn op_chdir(
 }
 
 fn op_set_timeout(
-  isolate: &mut Isolate,
+  isolate: &Isolate,
   base: &msg::Base,
   data: libdeno::deno_buf,
 ) -> Box<Op> {
@@ -333,16 +331,17 @@ fn op_set_timeout(
   let inner = base.inner_as_set_timeout().unwrap();
   // FIXME why is timeout a double if it's cast immediately to i64/u64??
   let val = inner.timeout() as i64;
-  isolate.timeout_due = if val >= 0 {
+  let timeout_due = if val >= 0 {
     Some(Instant::now() + Duration::from_millis(val as u64))
   } else {
     None
   };
+  isolate.set_timeout_due(timeout_due);
   ok_future(empty_buf())
 }
 
 fn op_set_env(
-  state: &Arc<IsolateState>,
+  state: &IsolateState,
   base: &msg::Base,
   data: libdeno::deno_buf,
 ) -> Box<Op> {
@@ -358,7 +357,7 @@ fn op_set_env(
 }
 
 fn op_env(
-  state: &Arc<IsolateState>,
+  state: &IsolateState,
   base: &msg::Base,
   data: libdeno::deno_buf,
 ) -> Box<Op> {
@@ -390,7 +389,7 @@ fn op_env(
 }
 
 fn op_fetch(
-  state: &Arc<IsolateState>,
+  state: &IsolateState,
   base: &msg::Base,
   data: libdeno::deno_buf,
 ) -> Box<Op> {
@@ -479,7 +478,7 @@ macro_rules! blocking {
 }
 
 fn op_make_temp_dir(
-  state: &Arc<IsolateState>,
+  state: &IsolateState,
   base: &msg::Base,
   data: libdeno::deno_buf,
 ) -> Box<Op> {
@@ -528,7 +527,7 @@ fn op_make_temp_dir(
 }
 
 fn op_mkdir(
-  state: &Arc<IsolateState>,
+  state: &IsolateState,
   base: &msg::Base,
   data: libdeno::deno_buf,
 ) -> Box<Op> {
@@ -548,7 +547,7 @@ fn op_mkdir(
 }
 
 fn op_chmod(
-  state: &Arc<IsolateState>,
+  state: &IsolateState,
   base: &msg::Base,
   data: libdeno::deno_buf,
 ) -> Box<Op> {
@@ -581,7 +580,7 @@ fn op_chmod(
 }
 
 fn op_open(
-  _state: &Arc<IsolateState>,
+  _state: &IsolateState,
   base: &msg::Base,
   data: libdeno::deno_buf,
 ) -> Box<Op> {
@@ -612,7 +611,7 @@ fn op_open(
 }
 
 fn op_close(
-  _state: &Arc<IsolateState>,
+  _state: &IsolateState,
   base: &msg::Base,
   data: libdeno::deno_buf,
 ) -> Box<Op> {
@@ -629,7 +628,7 @@ fn op_close(
 }
 
 fn op_shutdown(
-  _state: &Arc<IsolateState>,
+  _state: &IsolateState,
   base: &msg::Base,
   data: libdeno::deno_buf,
 ) -> Box<Op> {
@@ -655,7 +654,7 @@ fn op_shutdown(
 }
 
 fn op_read(
-  _state: &Arc<IsolateState>,
+  _state: &IsolateState,
   base: &msg::Base,
   data: libdeno::deno_buf,
 ) -> Box<Op> {
@@ -693,7 +692,7 @@ fn op_read(
 }
 
 fn op_write(
-  _state: &Arc<IsolateState>,
+  _state: &IsolateState,
   base: &msg::Base,
   data: libdeno::deno_buf,
 ) -> Box<Op> {
@@ -730,7 +729,7 @@ fn op_write(
 }
 
 fn op_remove(
-  state: &Arc<IsolateState>,
+  state: &IsolateState,
   base: &msg::Base,
   data: libdeno::deno_buf,
 ) -> Box<Op> {
@@ -760,7 +759,7 @@ fn op_remove(
 
 // Prototype https://github.com/denoland/deno/blob/golang/os.go#L171-L184
 fn op_read_file(
-  _config: &Arc<IsolateState>,
+  _config: &IsolateState,
   base: &msg::Base,
   data: libdeno::deno_buf,
 ) -> Box<Op> {
@@ -794,7 +793,7 @@ fn op_read_file(
 }
 
 fn op_copy_file(
-  state: &Arc<IsolateState>,
+  state: &IsolateState,
   base: &msg::Base,
   data: libdeno::deno_buf,
 ) -> Box<Op> {
@@ -846,7 +845,7 @@ fn get_mode(_perm: &fs::Permissions) -> u32 {
 }
 
 fn op_cwd(
-  _state: &Arc<IsolateState>,
+  _state: &IsolateState,
   base: &msg::Base,
   data: libdeno::deno_buf,
 ) -> Box<Op> {
@@ -872,7 +871,7 @@ fn op_cwd(
 }
 
 fn op_stat(
-  _config: &Arc<IsolateState>,
+  _config: &IsolateState,
   base: &msg::Base,
   data: libdeno::deno_buf,
 ) -> Box<Op> {
@@ -919,7 +918,7 @@ fn op_stat(
 }
 
 fn op_read_dir(
-  _state: &Arc<IsolateState>,
+  _state: &IsolateState,
   base: &msg::Base,
   data: libdeno::deno_buf,
 ) -> Box<Op> {
@@ -975,7 +974,7 @@ fn op_read_dir(
 }
 
 fn op_write_file(
-  state: &Arc<IsolateState>,
+  state: &IsolateState,
   base: &msg::Base,
   data: libdeno::deno_buf,
 ) -> Box<Op> {
@@ -995,7 +994,7 @@ fn op_write_file(
 }
 
 fn op_rename(
-  state: &Arc<IsolateState>,
+  state: &IsolateState,
   base: &msg::Base,
   data: libdeno::deno_buf,
 ) -> Box<Op> {
@@ -1015,7 +1014,7 @@ fn op_rename(
 }
 
 fn op_symlink(
-  state: &Arc<IsolateState>,
+  state: &IsolateState,
   base: &msg::Base,
   data: libdeno::deno_buf,
 ) -> Box<Op> {
@@ -1044,7 +1043,7 @@ fn op_symlink(
 }
 
 fn op_read_link(
-  _state: &Arc<IsolateState>,
+  _state: &IsolateState,
   base: &msg::Base,
   data: libdeno::deno_buf,
 ) -> Box<Op> {
@@ -1077,7 +1076,7 @@ fn op_read_link(
 }
 
 fn op_repl_start(
-  state: &Arc<IsolateState>,
+  state: &IsolateState,
   base: &msg::Base,
   data: libdeno::deno_buf,
 ) -> Box<Op> {
@@ -1108,7 +1107,7 @@ fn op_repl_start(
 }
 
 fn op_repl_readline(
-  _state: &Arc<IsolateState>,
+  _state: &IsolateState,
   base: &msg::Base,
   data: libdeno::deno_buf,
 ) -> Box<Op> {
@@ -1146,7 +1145,7 @@ fn op_repl_readline(
 }
 
 fn op_truncate(
-  state: &Arc<IsolateState>,
+  state: &IsolateState,
   base: &msg::Base,
   data: libdeno::deno_buf,
 ) -> Box<Op> {
@@ -1169,7 +1168,7 @@ fn op_truncate(
 }
 
 fn op_listen(
-  state: &Arc<IsolateState>,
+  state: &IsolateState,
   base: &msg::Base,
   data: libdeno::deno_buf,
 ) -> Box<Op> {
@@ -1235,7 +1234,7 @@ fn new_conn(cmd_id: u32, tcp_stream: TcpStream) -> OpResult {
 }
 
 fn op_accept(
-  state: &Arc<IsolateState>,
+  state: &IsolateState,
   base: &msg::Base,
   data: libdeno::deno_buf,
 ) -> Box<Op> {
@@ -1261,7 +1260,7 @@ fn op_accept(
 }
 
 fn op_dial(
-  state: &Arc<IsolateState>,
+  state: &IsolateState,
   base: &msg::Base,
   data: libdeno::deno_buf,
 ) -> Box<Op> {
@@ -1285,7 +1284,7 @@ fn op_dial(
 }
 
 fn op_metrics(
-  state: &Arc<IsolateState>,
+  state: &IsolateState,
   base: &msg::Base,
   data: libdeno::deno_buf,
 ) -> Box<Op> {
@@ -1309,7 +1308,7 @@ fn op_metrics(
 }
 
 fn op_resources(
-  _state: &Arc<IsolateState>,
+  _state: &IsolateState,
   base: &msg::Base,
   data: libdeno::deno_buf,
 ) -> Box<Op> {
@@ -1361,7 +1360,7 @@ fn subprocess_stdio_map(v: msg::ProcessStdio) -> std::process::Stdio {
 }
 
 fn op_run(
-  state: &Arc<IsolateState>,
+  state: &IsolateState,
   base: &msg::Base,
   data: libdeno::deno_buf,
 ) -> Box<Op> {
@@ -1429,7 +1428,7 @@ fn op_run(
 }
 
 fn op_run_status(
-  state: &Arc<IsolateState>,
+  state: &IsolateState,
   base: &msg::Base,
   data: libdeno::deno_buf,
 ) -> Box<Op> {