diff --git a/lib/_debugger.js b/lib/_debugger.js
index bb108347d4..c39a0ba58e 100644
--- a/lib/_debugger.js
+++ b/lib/_debugger.js
@@ -40,7 +40,7 @@ exports.start = function(argv, stdin, stdout) {
   stdout = stdout || process.stdout;
 
   var args = ['--debug-brk'].concat(argv),
-      interface = new Interface(stdin, stdout, args);
+      interface_ = new Interface(stdin, stdout, args);
 
   stdin.resume();
 
@@ -49,7 +49,7 @@ exports.start = function(argv, stdin, stdout) {
         'Please report this bug.');
     console.error(e.message);
     console.error(e.stack);
-    if (interface.child) interface.child.kill();
+    if (interface_.child) interface_.child.kill();
     process.exit(1);
   });
 };
@@ -700,7 +700,7 @@ function SourceUnderline(sourceText, position, repl) {
 
   // Colourize char if stdout supports colours
   if (repl.useColors) {
-    tail = tail.replace(/(.+?)([^\w]|$)/, '\033[32m$1\033[39m$2');
+    tail = tail.replace(/(.+?)([^\w]|$)/, '\u001b[32m$1\u001b[39m$2');
   }
 
   // Return source line with coloured char at `position`