diff --git a/lib/repl.js b/lib/repl.js
index 762423be2d..499f95b3be 100644
--- a/lib/repl.js
+++ b/lib/repl.js
@@ -1,6 +1,5 @@
 (function() {
-  var ACCESSOR, CoffeeScript, Module, REPL_PROMPT, REPL_PROMPT_CONTINUATION, SIMPLEVAR, Script, autocomplete, backlog, completeAttribute, completeVariable, enableColours, error, getCompletions, getPropertyNames, inspect, readline, repl, run, stdin, stdout;
-  var __hasProp = Object.prototype.hasOwnProperty;
+  var ACCESSOR, CoffeeScript, Module, REPL_PROMPT, REPL_PROMPT_CONTINUATION, SIMPLEVAR, Script, autocomplete, backlog, completeAttribute, completeVariable, enableColours, error, getCompletions, inspect, readline, repl, run, sandbox, stdin, stdout;
   CoffeeScript = require('./coffee-script');
   readline = require('readline');
   inspect = require('util').inspect;
@@ -18,43 +17,40 @@
     return stdout.write((err.stack || err.toString()) + '\n\n');
   };
   backlog = '';
-  run = (function() {
-    var sandbox;
-    sandbox = Script.createContext();
-    sandbox.global = sandbox.root = sandbox.GLOBAL = sandbox;
-    return function(buffer) {
-      var code, returnValue, _;
-      if (!buffer.toString().trim() && !backlog) {
-        repl.prompt();
-        return;
-      }
-      code = backlog += buffer;
-      if (code[code.length - 1] === '\\') {
-        backlog = "" + backlog.slice(0, -1) + "\n";
-        repl.setPrompt(REPL_PROMPT_CONTINUATION);
-        repl.prompt();
-        return;
-      }
-      repl.setPrompt(REPL_PROMPT);
-      backlog = '';
-      try {
-        _ = sandbox._;
-        returnValue = CoffeeScript.eval("_=(" + code + "\n)", {
-          sandbox: sandbox,
-          filename: 'repl',
-          modulename: 'repl'
-        });
-        if (returnValue === void 0) {
-          sandbox._ = _;
-        } else {
-          process.stdout.write(inspect(returnValue, false, 2, enableColours) + '\n');
-        }
-      } catch (err) {
-        error(err);
+  sandbox = Script.createContext();
+  sandbox.global = sandbox.root = sandbox.GLOBAL = sandbox;
+  run = function(buffer) {
+    var code, returnValue, _;
+    if (!buffer.toString().trim() && !backlog) {
+      repl.prompt();
+      return;
+    }
+    code = backlog += buffer;
+    if (code[code.length - 1] === '\\') {
+      backlog = "" + backlog.slice(0, -1) + "\n";
+      repl.setPrompt(REPL_PROMPT_CONTINUATION);
+      repl.prompt();
+      return;
+    }
+    repl.setPrompt(REPL_PROMPT);
+    backlog = '';
+    try {
+      _ = sandbox._;
+      returnValue = CoffeeScript.eval("_=(" + code + "\n)", {
+        sandbox: sandbox,
+        filename: 'repl',
+        modulename: 'repl'
+      });
+      if (returnValue === void 0) {
+        sandbox._ = _;
+      } else {
+        process.stdout.write(inspect(returnValue, false, 2, enableColours) + '\n');
       }
-      return repl.prompt();
-    };
-  })();
+    } catch (err) {
+      error(err);
+    }
+    return repl.prompt();
+  };
   ACCESSOR = /\s*([\w\.]+)(?:\.(\w*))$/;
   SIMPLEVAR = /\s*(\w*)$/i;
   autocomplete = function(text) {
@@ -65,19 +61,20 @@
     if (match = text.match(ACCESSOR)) {
       all = match[0], obj = match[1], prefix = match[2];
       try {
-        val = Script.runInThisContext(obj);
+        val = Script.runInContext(obj, sandbox);
       } catch (error) {
-        return [[], text];
+        return;
       }
-      completions = getCompletions(prefix, getPropertyNames(val));
+      completions = getCompletions(prefix, Object.getOwnPropertyNames(val));
       return [completions, prefix];
     }
   };
   completeVariable = function(text) {
-    var completions, free, scope, _ref;
+    var completions, free, possibilities, vars, _ref;
     if (free = (_ref = text.match(SIMPLEVAR)) != null ? _ref[1] : void 0) {
-      scope = Script.runInThisContext('this');
-      completions = getCompletions(free, CoffeeScript.RESERVED.concat(getPropertyNames(scope)));
+      vars = Script.runInContext('Object.getOwnPropertyNames(this)', sandbox);
+      possibilities = vars.concat(CoffeeScript.RESERVED);
+      completions = getCompletions(free, possibilities);
       return [completions, free];
     }
   };
@@ -92,15 +89,6 @@
     }
     return _results;
   };
-  getPropertyNames = function(obj) {
-    var name, _results;
-    _results = [];
-    for (name in obj) {
-      if (!__hasProp.call(obj, name)) continue;
-      _results.push(name);
-    }
-    return _results;
-  };
   process.on('uncaughtException', error);
   if (readline.createInterface.length < 3) {
     repl = readline.createInterface(stdin, autocomplete);
diff --git a/src/repl.coffee b/src/repl.coffee
index 9a6bc40816..90454e814f 100644
--- a/src/repl.coffee
+++ b/src/repl.coffee
@@ -31,39 +31,39 @@ error = (err) ->
 # The current backlog of multi-line code.
 backlog = ''
 
+# The REPL context; must be visible outside `run` to allow for tab completion
+sandbox = Script.createContext()
+sandbox.global = sandbox.root = sandbox.GLOBAL = sandbox
+
 # The main REPL function. **run** is called every time a line of code is entered.
 # Attempt to evaluate the command. If there's an exception, print it out instead
 # of exiting.
-run = do ->
-  # The REPL context
-  sandbox = Script.createContext()
-  sandbox.global = sandbox.root = sandbox.GLOBAL = sandbox
-  (buffer) ->
-    if !buffer.toString().trim() and !backlog
-      repl.prompt()
-      return
-    code = backlog += buffer
-    if code[code.length - 1] is '\\'
-      backlog = "#{backlog[...-1]}\n"
-      repl.setPrompt REPL_PROMPT_CONTINUATION
-      repl.prompt()
-      return
-    repl.setPrompt REPL_PROMPT
-    backlog = ''
-    try
-      _ = sandbox._
-      returnValue = CoffeeScript.eval "_=(#{code}\n)", {
-        sandbox,
-        filename: 'repl'
-        modulename: 'repl'
-      }
-      if returnValue is undefined
-        sandbox._ = _
-      else
-        process.stdout.write inspect(returnValue, no, 2, enableColours) + '\n'
-    catch err
-      error err
+run = (buffer) ->
+  if !buffer.toString().trim() and !backlog
+    repl.prompt()
+    return
+  code = backlog += buffer
+  if code[code.length - 1] is '\\'
+    backlog = "#{backlog[...-1]}\n"
+    repl.setPrompt REPL_PROMPT_CONTINUATION
     repl.prompt()
+    return
+  repl.setPrompt REPL_PROMPT
+  backlog = ''
+  try
+    _ = sandbox._
+    returnValue = CoffeeScript.eval "_=(#{code}\n)", {
+      sandbox,
+      filename: 'repl'
+      modulename: 'repl'
+    }
+    if returnValue is undefined
+      sandbox._ = _
+    else
+      process.stdout.write inspect(returnValue, no, 2, enableColours) + '\n'
+  catch err
+    error err
+  repl.prompt()
 
 ## Autocompletion
 
@@ -80,27 +80,24 @@ completeAttribute = (text) ->
   if match = text.match ACCESSOR
     [all, obj, prefix] = match
     try
-      val = Script.runInThisContext obj
+      val = Script.runInContext obj, sandbox
     catch error
-      return [[], text]
-    completions = getCompletions prefix, getPropertyNames val
+      return
+    completions = getCompletions prefix, Object.getOwnPropertyNames val
     [completions, prefix]
 
 # Attempt to autocomplete an in-scope free variable: `one`.
 completeVariable = (text) ->
-  if free = text.match(SIMPLEVAR)?[1]
-    scope = Script.runInThisContext 'this'
-    completions = getCompletions free, CoffeeScript.RESERVED.concat(getPropertyNames scope)
+  if free = (text.match SIMPLEVAR)?[1]
+    vars = Script.runInContext 'Object.getOwnPropertyNames(this)', sandbox
+    possibilities = vars.concat CoffeeScript.RESERVED
+    completions = getCompletions free, possibilities
     [completions, free]
 
 # Return elements of candidates for which `prefix` is a prefix.
 getCompletions = (prefix, candidates) ->
   (el for el in candidates when el.indexOf(prefix) is 0)
 
-# Return all "own" properties of an object.
-getPropertyNames = (obj) ->
-  (name for own name of obj)
-
 # Make sure that uncaught exceptions don't kill the REPL.
 process.on 'uncaughtException', error