diff --git a/lib/configure.js b/lib/configure.js
index 853ef1f..268c336 100644
--- a/lib/configure.js
+++ b/lib/configure.js
@@ -13,6 +13,7 @@ var fs = require('graceful-fs')
   , semver = require('semver')
   , mkdirp = require('mkdirp')
   , cp = require('child_process')
+  , extend = require('util')._extend
   , spawn = cp.spawn
   , execFile = cp.execFile
   , win = process.platform == 'win32'
@@ -72,7 +73,9 @@ function configure (gyp, argv, callback) {
   }
 
   function checkPythonVersion () {
-    var env = { TERM: 'dumb', PATH: process.env.PATH }
+    var env = extend({}, process.env);
+    env.TERM = 'dumb';
+
     execFile(python, ['-c', 'import platform; print(platform.python_version());'], { env: env }, function (err, stdout) {
       if (err) {
         return callback(err)