diff --git a/lib/cmd/cov.js b/lib/cmd/cov.js
index cf3131f4..e123a005 100644
--- a/lib/cmd/cov.js
+++ b/lib/cmd/cov.js
@@ -67,6 +67,12 @@ class CovCommand extends Command {
     for (const exclude of excludes) {
       this.addExclude(exclude);
     }
+    if (context.argv.parallel) {
+      env.ENABLE_MOCHA_PARALLEL = 'true';
+    }
+    if (context.argv.parallel && context.argv['auto-agent']) {
+      env.AUTO_AGENT = 'true';
+    }
 
     const opt = {
       cwd,
@@ -136,7 +142,8 @@ class CovCommand extends Command {
   }
 
   getTestCommandAndArgs() {
-    return [ require.resolve('mocha/bin/_mocha') ];
+    const mochaFile = process.env.MOCHA_FILE || require.resolve('mocha/bin/_mocha');
+    return [ mochaFile ];
   }
 }
 
diff --git a/test/fixtures/bin/fake_mocha.js b/test/fixtures/bin/fake_mocha.js
old mode 100644
new mode 100755
index 87f8f813..314856fa
--- a/test/fixtures/bin/fake_mocha.js
+++ b/test/fixtures/bin/fake_mocha.js
@@ -1,2 +1,4 @@
+#!/usr/bin/env node
+
 console.log('env.AUTO_AGENT:', process.env.AUTO_AGENT);
 console.log('env.ENABLE_MOCHA_PARALLEL:', process.env.ENABLE_MOCHA_PARALLEL);
diff --git a/test/lib/cmd/cov.test.js b/test/lib/cmd/cov.test.js
index b60d28b0..ddfc0b21 100644
--- a/test/lib/cmd/cov.test.js
+++ b/test/lib/cmd/cov.test.js
@@ -185,4 +185,19 @@ describe('test/lib/cmd/cov.test.js', () => {
       .expect('stdout', /Statements/)
       .end();
   });
+
+  it('env should work', async () => {
+    mm(process.env, 'TESTS', 'test/**/*.test.js');
+    return coffee.fork(eggBin, [ 'cov', '--parallel' ], {
+      cwd: path.join(__dirname, '../../fixtures/test-demo-app'),
+      env: Object.assign({
+        MOCHA_FILE: path.join(__dirname, '../../fixtures/bin/fake_mocha.js'),
+      }, process.env),
+    })
+      // .debug()
+      .expect('stdout', /env\.AUTO_AGENT: true/)
+      .expect('stdout', /env\.ENABLE_MOCHA_PARALLEL: true/)
+      .expect('code', 0)
+      .end();
+  });
 });