diff --git a/test/gulpfile.js b/test/gulpfile.js
index c020ff76..6d4ac5a0 100644
--- a/test/gulpfile.js
+++ b/test/gulpfile.js
@@ -22,7 +22,6 @@ const execa = require('execa');
 const path = require('path');
 const del = require('del');
 const linkSync = require('../util').linkSync;
-const merge = require('merge2');
 
 // gulp-help monkeypatches tasks to have an additional description parameter
 const gulp = help(_gulp);
@@ -52,17 +51,30 @@ gulp.task('internal.test.link.add', 'Link local copies of dependencies', () => {
 gulp.task('internal.test.test', 'Run API-level tests', () => {
   // run mocha tests matching a glob with a pre-required fixture,
   // returning the associated gulp stream
-  const runTestsWithFixture = (glob, fixture) => gulp
-    .src(glob)
-    .pipe(mocha({
-      reporter: 'mocha-jenkins-reporter',
-      require: `${testDir}/fixtures/${fixture}.js`
-    }));
-  const interopTest = `${testDir}/interop/interop_test.js`;
-  const tasks = [].concat(
-    ['native_native'/*, 'js_js'*/]
-      .map((fixture) => runTestsWithFixture(`${apiTestDir}/*.js`, fixture)),
-    ['native_native', 'native_js'/*, 'js_native', 'js_js'*/]
-      .map((fixture) => runTestsWithFixture(interopTest, fixture)))
-  return merge(tasks);
+  const runTestsWithFixture = (glob, fixture) => new Promise((resolve, reject) => {
+    const server = fixture.split('_')[0];
+    const client = fixture.split('_')[1];
+    console.log(`Running ${glob} with ${server} server + ${client} client`);
+    gulp.src(glob)
+      .pipe(mocha({
+        reporter: 'mocha-jenkins-reporter',
+        require: `${testDir}/fixtures/${fixture}.js`
+      }))
+      .resume() // put the stream in flowing mode
+      .on('end', resolve)
+      .on('error', reject);
+  });
+  const apiTestGlob = `${apiTestDir}/*.js`;
+  const interopTestGlob = `${testDir}/interop/interop_sanity_test.js`;
+  const runTestsArgPairs = [
+    [apiTestGlob, 'native_native'],
+    [apiTestGlob, 'js_js'],
+    [interopTestGlob, 'native_native'],
+    [interopTestGlob, 'native_js'],
+    [interopTestGlob, 'js_native'],
+    [interopTestGlob, 'js_js']
+  ];
+  return runTestsArgPairs.reduce((previousPromise, argPair) => {
+    return previousPromise.then(runTestsWithFixture.bind(null, argPair[0], argPair[1]));
+  }, Promise.resolve());
 });