diff --git a/js/chmod.ts b/js/chmod.ts
new file mode 100644
index 00000000000000..adc94d2c1c9336
--- /dev/null
+++ b/js/chmod.ts
@@ -0,0 +1,24 @@
+import * as fbs from "gen/msg_generated";
+import { flatbuffers } from "flatbuffers";
+import * as dispatch from "./dispatch";
+/**
+ * Synchronously changes the file permissions.
+ *
+ *     import { chmodSync } from "deno";
+ *     chmodSync(path, mode);
+ */
+export function chmodSync(path: string, mode: number): void {
+  dispatch.sendSync(...req(path, mode));
+}
+function req(
+  path: string,
+  mode: number
+): [flatbuffers.Builder, fbs.Any, flatbuffers.Offset] {
+  const builder = new flatbuffers.Builder();
+  const path_ = builder.createString(path);
+  fbs.Chmod.startChmod(builder);
+  fbs.Chmod.addPath(builder, path_);
+  fbs.Chmod.addMode(builder, mode);
+  const msg = fbs.Chmod.endChmod(builder);
+  return [builder, fbs.Any.Chmod, msg];
+}
diff --git a/js/chmod_test.ts b/js/chmod_test.ts
new file mode 100644
index 00000000000000..59983e7dfd851a
--- /dev/null
+++ b/js/chmod_test.ts
@@ -0,0 +1,25 @@
+// Copyright 2018 the Deno authors. All rights reserved. MIT license.
+import { test, testPerm, assert, assertEqual } from "./test_util.ts";
+import * as deno from "deno";
+testPerm({ write: true }, function chmodSyncSuccess() {
+  const enc = new TextEncoder();
+  const data = enc.encode("Hello");
+  const filename = deno.makeTempDirSync() + "/test.txt";
+  deno.writeFileSync(filename, data, 0o666);
+  let fileInfo = deno.statSync(filename);
+  console.log(fileInfo.mode, 0o666); // This is printing 33206 438
+  deno.chmodSync(filename, 0o777);
+  fileInfo = deno.statSync(filename);
+  assertEqual(fileInfo.mode, 0o777);
+});
+testPerm({ write: false }, function chmodSyncPerm() {
+  let err;
+  try {
+    const filename = deno.makeTempDirSync() + "/test.txt";
+    deno.chmodSync(filename, 0o777);
+  } catch (e) {
+    err = e;
+  }
+  assertEqual(err.kind, deno.ErrorKind.PermissionDenied);
+  assertEqual(err.name, "PermissionDenied");
+});
diff --git a/js/compiler.ts b/js/compiler.ts
index f0f82ffb111fae..cf4d1906af83d3 100644
--- a/js/compiler.ts
+++ b/js/compiler.ts
@@ -418,10 +418,10 @@ export class DenoCompiler
    */
   compile(moduleMetaData: ModuleMetaData): OutputCode {
     const recompile = !!this.recompile;
-    this._log(
-        "compiler.compile",
-        { filename: moduleMetaData.fileName, recompile }
-    );
+    this._log("compiler.compile", {
+      filename: moduleMetaData.fileName,
+      recompile
+    });
     if (!recompile && moduleMetaData.outputCode) {
       return moduleMetaData.outputCode;
     }
diff --git a/js/compiler_test.ts b/js/compiler_test.ts
index fef18ec3d26bca..e3be535bd45f4e 100644
--- a/js/compiler_test.ts
+++ b/js/compiler_test.ts
@@ -461,16 +461,24 @@ test(function compilerGetScriptFileNames() {
 test(function compilerRecompileFlag() {
   setup();
   compilerInstance.run("foo/bar.ts", "/root/project");
-  assertEqual(getEmitOutputStack.length, 1, "Expected only a single emitted file.");
+  assertEqual(
+    getEmitOutputStack.length,
+    1,
+    "Expected only a single emitted file."
+  );
   // running compiler against same file should use cached code
   compilerInstance.run("foo/bar.ts", "/root/project");
-  assertEqual(getEmitOutputStack.length, 1, "Expected only a single emitted file.");
+  assertEqual(
+    getEmitOutputStack.length,
+    1,
+    "Expected only a single emitted file."
+  );
   compilerInstance.recompile = true;
   compilerInstance.run("foo/bar.ts", "/root/project");
   assertEqual(getEmitOutputStack.length, 2, "Expected two emitted file.");
   assert(
-      getEmitOutputStack[0] === getEmitOutputStack[1],
-      "Expected same file to be emitted twice."
+    getEmitOutputStack[0] === getEmitOutputStack[1],
+    "Expected same file to be emitted twice."
   );
   teardown();
 });
diff --git a/js/deno.ts b/js/deno.ts
index 3bbda69e8f23fd..3f5567138ab233 100644
--- a/js/deno.ts
+++ b/js/deno.ts
@@ -15,4 +15,5 @@ export { ErrorKind, DenoError } from "./errors";
 export { libdeno } from "./libdeno";
 export { arch, platform } from "./platform";
 export { trace } from "./trace";
+export { chmodSync } from "./chmod";
 export const args: string[] = [];
diff --git a/js/read_link.ts b/js/read_link.ts
index 6bd613389450c7..38db09d62f331b 100644
--- a/js/read_link.ts
+++ b/js/read_link.ts
@@ -24,9 +24,7 @@ export async function readlink(name: string): Promise<string> {
   return res(await dispatch.sendAsync(...req(name)));
 }
 
-function req(
-  name: string
-): [flatbuffers.Builder, fbs.Any, flatbuffers.Offset] {
+function req(name: string): [flatbuffers.Builder, fbs.Any, flatbuffers.Offset] {
   const builder = new flatbuffers.Builder();
   const name_ = builder.createString(name);
   fbs.Readlink.startReadlink(builder);
diff --git a/js/unit_tests.ts b/js/unit_tests.ts
index 578a65c6da539a..1ea281cb527f74 100644
--- a/js/unit_tests.ts
+++ b/js/unit_tests.ts
@@ -2,6 +2,7 @@
 // This test is executed as part of tools/test.py
 // But it can also be run manually: ./out/debug/deno js/unit_tests.ts
 import "./compiler_test.ts";
+import "./chmod_test.ts";
 import "./console_test.ts";
 import "./fetch_test.ts";
 import "./os_test.ts";
diff --git a/src/handlers.rs b/src/handlers.rs
index 964baabf8d8e93..a2175e0b2d746e 100644
--- a/src/handlers.rs
+++ b/src/handlers.rs
@@ -15,6 +15,8 @@ use msg;
 use remove_dir_all::remove_dir_all;
 use std;
 use std::fs;
+extern crate libc;
+use std::ffi::CString;
 #[cfg(any(unix))]
 use std::os::unix::fs::PermissionsExt;
 use std::path::Path;
@@ -47,6 +49,7 @@ pub extern "C" fn msg_from_js(i: *const isolate, buf: deno_buf) {
     msg::Any::Start => handle_start,
     msg::Any::CodeFetch => handle_code_fetch,
     msg::Any::CodeCache => handle_code_cache,
+    msg::Any::Chmod => handle_chmod,
     msg::Any::Environ => handle_env,
     msg::Any::FetchReq => handle_fetch_req,
     msg::Any::TimerStart => handle_timer_start,
@@ -147,7 +150,7 @@ fn permission_denied() -> DenoError {
 fn not_implemented() -> DenoError {
   DenoError::from(std::io::Error::new(
     std::io::ErrorKind::Other,
-    "Not implemented"
+    "Not implemented",
   ))
 }
 
@@ -302,7 +305,8 @@ fn handle_env(i: *const isolate, base: &msg::Base) -> Box<Op> {
           ..Default::default()
         },
       )
-    }).collect();
+    })
+    .collect();
   let tables = builder.create_vector(&vars);
   let msg = msg::EnvironRes::create(
     builder,
@@ -415,7 +419,8 @@ where
     .and_then(|_| {
       cb();
       Ok(())
-    }).select(cancel_rx)
+    })
+    .select(cancel_rx)
     .map(|_| ())
     .map_err(|_| ());
 
@@ -704,6 +709,27 @@ fn handle_symlink(i: *const isolate, base: &msg::Base) -> Box<Op> {
   }
 }
 
+fn handle_chmod(i: *const isolate, base: &msg::Base) -> Box<Op> {
+  let deno = from_c(i);
+  if !deno.flags.allow_write {
+    return odd_future(permission_denied());
+  };
+  let msg = base.msg_as_chmod().unwrap();
+  let path = msg.path().unwrap();
+  let mode = msg.mode();
+  debug!("handle_chmod {} {}", path, mode);
+  if cfg!(target_family = "unix") {
+    Box::new(futures::future::result(|| -> OpResult {
+      let path_as_cstring = CString::new(path).unwrap();
+      unsafe {
+        libc::chmod(path_as_cstring.as_ptr(), mode);
+      }
+      Ok(None)
+    }()))
+  } else {
+    Box::new(futures::future::result(|| -> OpResult { Ok(None) }()))
+  }
+}
 fn handle_read_link(_i: *const isolate, base: &msg::Base) -> Box<Op> {
   let msg = base.msg_as_readlink().unwrap();
   let cmd_id = base.cmd_id();
diff --git a/src/msg.fbs b/src/msg.fbs
index 6358668b7ede37..478d8d2dcdd547 100644
--- a/src/msg.fbs
+++ b/src/msg.fbs
@@ -4,6 +4,7 @@ union Any {
   CodeFetch,
   CodeFetchRes,
   CodeCache,
+  Chmod,
   Exit,
   TimerStart,
   TimerReady,
@@ -222,6 +223,12 @@ table Stat {
   lstat: bool;
 }
 
+table Chmod {
+  path: string;
+  mode: uint32;
+}
+
+
 table StatRes {
   is_file: bool;
   is_symlink: bool;