diff --git a/package.json b/package.json
index 562a182a8c..e72c03f97b 100644
--- a/package.json
+++ b/package.json
@@ -309,7 +309,7 @@
   "dependencies": {
     "browser-stdout": "1.3.0",
     "commander": "2.9.0",
-    "debug": "2.6.0",
+    "debug": "2.6.8",
     "diff": "3.2.0",
     "escape-string-regexp": "1.0.5",
     "glob": "7.1.1",
diff --git a/test/integration/helpers.js b/test/integration/helpers.js
index 025770dd6b..179ecc1b17 100644
--- a/test/integration/helpers.js
+++ b/test/integration/helpers.js
@@ -2,7 +2,6 @@
 
 var spawn = require('child_process').spawn;
 var path = require('path');
-var fs = require('fs');
 var baseReporter = require('../../lib/reporters/base');
 
 module.exports = {
@@ -41,47 +40,6 @@ module.exports = {
     });
   },
 
-  /**
-   * Invokes the mocha binary on the code of the body of the function.
-   * Accepts an array of additional command line args to pass. The callback is
-   * invoked with a summary of the run, in addition to its output. The summary
-   * includes the number of passing, pending, and failing tests, as well as the
-   * exit code. Useful for testing different reporters.
-   *
-   * Example response:
-   * {
-   *   pending: 0,
-   *   passing: 0,
-   *   failing: 1,
-   *   code:    1,
-   *   output:  '...'
-   * }
-   *
-   * @param {function} fixture
-   * @param {array}    args
-   * @param {function} fn
-   */
-  runMochaFunction: function (fixture, args, fn) {
-    var path = resolveFixturePath(fixture.name + '.js' || 'tempfile.js');
-    args = args || [];
-
-    var fixtureContent = 'var fn = ' + fixture.toString() + '; fn()';
-    fs.writeFileSync(path, fixtureContent, 'utf8');
-
-    function cleanup () {
-      fs.unlink(path);
-      fn.apply(this, arguments);
-    }
-
-    invokeMocha(args.concat(['-C', path]), function (err, res) {
-      if (err) {
-        return cleanup(err);
-      }
-
-      cleanup(null, getSummary(res));
-    });
-  },
-
   /**
    * Invokes the mocha binary for the given fixture using the JSON reporter,
    * returning the parsed output, as well as exit code.
@@ -157,10 +115,12 @@ module.exports = {
 
 function invokeMocha (args, fn) {
   var output, mocha, listener;
-
+  // ensure DEBUG doesn't kill tests
+  var env = Object.assign({}, process.env);
+  delete env.DEBUG;
   output = '';
   args = [path.join('bin', 'mocha')].concat(args);
-  mocha = spawn(process.execPath, args);
+  mocha = spawn(process.execPath, args, {env: env});
 
   listener = function (data) {
     output += data;