diff --git a/test/parallel/test-benchmark-crypto.js b/test/parallel/test-benchmark-crypto.js
index 682c1276430609..5750a4e2afdadf 100644
--- a/test/parallel/test-benchmark-crypto.js
+++ b/test/parallel/test-benchmark-crypto.js
@@ -26,8 +26,9 @@ const argv = ['--set', 'algo=sha256',
               '--set', 'v=crypto',
               '--set', 'writes=1',
               'crypto'];
-
-const child = fork(runjs, argv, { env: { NODEJS_BENCHMARK_ZERO_ALLOWED: 1 } });
+const env = Object.assign({}, process.env,
+                          { NODEJS_BENCHMARK_ZERO_ALLOWED: 1 });
+const child = fork(runjs, argv, { env });
 child.on('exit', (code, signal) => {
   assert.strictEqual(code, 0);
   assert.strictEqual(signal, null);
diff --git a/test/parallel/test-benchmark-timers.js b/test/parallel/test-benchmark-timers.js
index 27844b427ccd1d..991ffda7186e72 100644
--- a/test/parallel/test-benchmark-timers.js
+++ b/test/parallel/test-benchmark-timers.js
@@ -15,7 +15,10 @@ const argv = ['--set', 'type=depth',
               '--set', 'thousands=0.001',
               'timers'];
 
-const child = fork(runjs, argv, { env: { NODEJS_BENCHMARK_ZERO_ALLOWED: 1 } });
+const env = Object.assign({}, process.env,
+                          { NODEJS_BENCHMARK_ZERO_ALLOWED: 1 });
+
+const child = fork(runjs, argv, { env });
 child.on('exit', (code, signal) => {
   assert.strictEqual(code, 0);
   assert.strictEqual(signal, null);
diff --git a/test/parallel/test-env-var-no-warnings.js b/test/parallel/test-env-var-no-warnings.js
index 3a99cbc112d8b9..e2a11656f33df2 100644
--- a/test/parallel/test-env-var-no-warnings.js
+++ b/test/parallel/test-env-var-no-warnings.js
@@ -6,7 +6,8 @@ const cp = require('child_process');
 if (process.argv[2] === 'child') {
   process.emitWarning('foo');
 } else {
-  function test(env) {
+  function test(newEnv) {
+    const env = Object.assign({}, process.env, newEnv);
     const cmd = `"${process.execPath}" "${__filename}" child`;
 
     cp.exec(cmd, { env }, common.mustCall((err, stdout, stderr) => {
diff --git a/test/parallel/test-tls-env-bad-extra-ca.js b/test/parallel/test-tls-env-bad-extra-ca.js
index ece93f33539d71..5c6e47d52a654a 100644
--- a/test/parallel/test-tls-env-bad-extra-ca.js
+++ b/test/parallel/test-tls-env-bad-extra-ca.js
@@ -15,10 +15,10 @@ if (process.env.CHILD) {
   return tls.createServer({});
 }
 
-const env = {
+const env = Object.assign({}, process.env, {
   CHILD: 'yes',
   NODE_EXTRA_CA_CERTS: `${common.fixturesDir}/no-such-file-exists`,
-};
+});
 
 const opts = {
   env: env,
diff --git a/test/parallel/test-tls-env-extra-ca.js b/test/parallel/test-tls-env-extra-ca.js
index f55167c53c58c9..80d9cc9ec3ecef 100644
--- a/test/parallel/test-tls-env-extra-ca.js
+++ b/test/parallel/test-tls-env-extra-ca.js
@@ -32,11 +32,11 @@ const server = tls.createServer(options, common.mustCall(function(s) {
   s.end('bye');
   server.close();
 })).listen(0, common.mustCall(function() {
-  const env = {
+  const env = Object.assign({}, process.env, {
     CHILD: 'yes',
     PORT: this.address().port,
     NODE_EXTRA_CA_CERTS: fixtures.path('keys', 'ca1-cert.pem')
-  };
+  });
 
   fork(__filename, { env: env }).on('exit', common.mustCall(function(status) {
     assert.strictEqual(status, 0, 'client did not succeed in connecting');
diff --git a/test/sequential/test-benchmark-child-process.js b/test/sequential/test-benchmark-child-process.js
index 168f99445d96ba..f993238549fca4 100644
--- a/test/sequential/test-benchmark-child-process.js
+++ b/test/sequential/test-benchmark-child-process.js
@@ -8,13 +8,22 @@ const path = require('path');
 
 const runjs = path.join(__dirname, '..', '..', 'benchmark', 'run.js');
 
-const child = fork(runjs, ['--set', 'dur=0',
-                           '--set', 'n=1',
-                           '--set', 'len=1',
-                           '--set', 'params=1',
-                           '--set', 'methodName=execSync',
-                           'child_process'],
-                   { env: { NODEJS_BENCHMARK_ZERO_ALLOWED: 1 } });
+const env = Object.assign({}, process.env,
+                          { NODEJS_BENCHMARK_ZERO_ALLOWED: 1 });
+
+const child = fork(
+  runjs,
+  [
+    '--set', 'dur=0',
+    '--set', 'n=1',
+    '--set', 'len=1',
+    '--set', 'params=1',
+    '--set', 'methodName=execSync',
+    'child_process'
+  ],
+  { env }
+);
+
 child.on('exit', (code, signal) => {
   assert.strictEqual(code, 0);
   assert.strictEqual(signal, null);
diff --git a/test/sequential/test-benchmark-net.js b/test/sequential/test-benchmark-net.js
index 43f712701d7f89..b2d360328504fb 100644
--- a/test/sequential/test-benchmark-net.js
+++ b/test/sequential/test-benchmark-net.js
@@ -15,12 +15,14 @@ const path = require('path');
 
 const runjs = path.join(__dirname, '..', '..', 'benchmark', 'run.js');
 
+const env = Object.assign({}, process.env,
+                          { NODEJS_BENCHMARK_ZERO_ALLOWED: 1 });
 const child = fork(runjs,
                    ['--set', 'dur=0',
                     '--set', 'len=1024',
                     '--set', 'type=buf',
                     'net'],
-                   { env: { NODEJS_BENCHMARK_ZERO_ALLOWED: 1 } });
+                   { env });
 child.on('exit', (code, signal) => {
   assert.strictEqual(code, 0);
   assert.strictEqual(signal, null);