diff --git a/lib/God/ClusterMode.js b/lib/God/ClusterMode.js
index 10619b0fe..cfe3bdf9f 100644
--- a/lib/God/ClusterMode.js
+++ b/lib/God/ClusterMode.js
@@ -11,6 +11,7 @@
  * @project PM2
  */
 var cluster       = require('cluster');
+var path          = require('path');
 var Utility       = require('../Utility.js');
 var pkg           = require('../../package.json');
 
@@ -34,9 +35,12 @@ module.exports = function ClusterMode(God) {
     var clu = null;
 
     console.log(`App [${env_copy.name}:${env_copy.pm_id}] starting in -cluster mode-`)
+    var initEnvScript = path.resolve(__dirname, '..', 'ProcessContainerClusterInitEnv.js');
+    var execArgv = ['--require', initEnvScript];
     if (env_copy.node_args && Array.isArray(env_copy.node_args)) {
-      cluster.settings.execArgv = env_copy.node_args;
+      execArgv = execArgv.concat(env_copy.node_args);
     }
+    cluster.settings.execArgv = execArgv;
 
     env_copy._pm2_version = pkg.version;
 
diff --git a/lib/ProcessContainerClusterInitEnv.js b/lib/ProcessContainerClusterInitEnv.js
new file mode 100644
index 000000000..b74a1a4b9
--- /dev/null
+++ b/lib/ProcessContainerClusterInitEnv.js
@@ -0,0 +1,16 @@
+/**
+ * Copyright 2013-present the PM2 project authors. All rights reserved.
+ * Use of this source code is governed by a license that
+ * can be found in the LICENSE file.
+ *
+ * Expand the pm2_env JSON string into individual process.env entries.
+ * This must run before any user --require modules so they can access
+ * the configured environment variables.
+ */
+
+if (process.env.pm2_env) {
+  var pm2_env = JSON.parse(process.env.pm2_env);
+  for (var k in pm2_env) {
+    process.env[k] = pm2_env[k];
+  }
+}
diff --git a/test/fixtures/require-env-capture.js b/test/fixtures/require-env-capture.js
new file mode 100644
index 000000000..4875865a4
--- /dev/null
+++ b/test/fixtures/require-env-capture.js
@@ -0,0 +1,12 @@
+var fs = require('fs');
+
+// Capture the env var at --require time and write it to a result file.
+// PM2_REQUIRE_RESULT_FILE tells us where to write, so cluster and fork
+// tests can share this fixture without colliding.
+var resultFile = process.env.PM2_REQUIRE_RESULT_FILE;
+if (resultFile) {
+  fs.writeFileSync(
+    resultFile,
+    JSON.stringify({ value: process.env.PM2_TEST_REQUIRE_VAR || null })
+  );
+}
diff --git a/test/programmatic/require_cluster_env.mocha.js b/test/programmatic/require_cluster_env.mocha.js
new file mode 100644
index 000000000..18ad74b6c
--- /dev/null
+++ b/test/programmatic/require_cluster_env.mocha.js
@@ -0,0 +1,87 @@
+
+process.chdir(__dirname)
+
+var fs = require('fs')
+var path = require('path')
+var PM2 = require('../..')
+var should = require('should')
+
+var CLUSTER_RESULT = path.join(__dirname, '..', 'require-env-cluster-result.json')
+var FORK_RESULT    = path.join(__dirname, '..', 'require-env-fork-result.json')
+var REQUIRE_SCRIPT = path.resolve(__dirname, '../fixtures/require-env-capture.js')
+
+// In cluster mode PM2 serialises env vars into a pm2_env JSON string and the
+// entry wrapper (ProcessContainer.js) unpacks it.  Node.js processes execArgv
+// (including --require flags) *before* that wrapper runs, so without the fix a
+// library loaded via --require would see the raw JSON blob rather than the
+// individual env vars.  ProcessContainerClusterInitEnv.js is prepended as the
+// first --require so the env is expanded before any user --require runs.
+
+describe('--require script env var visibility', function () {
+  this.timeout(15000)
+
+  before(function (done) {
+    try { fs.unlinkSync(CLUSTER_RESULT) } catch (e) {}
+    try { fs.unlinkSync(FORK_RESULT) } catch (e) {}
+    PM2.delete('all', function () { done() })
+  })
+
+  after(function (done) {
+    try { fs.unlinkSync(CLUSTER_RESULT) } catch (e) {}
+    try { fs.unlinkSync(FORK_RESULT) } catch (e) {}
+    PM2.kill(done)
+  })
+
+  afterEach(function (done) {
+    PM2.delete('all', done)
+  })
+
+  it('should expose PM2 env vars to --require scripts in cluster mode', function (done) {
+    PM2.start({
+      script: './../fixtures/empty.js',
+      name: 'test-require-env-cluster',
+      exec_mode: 'cluster',
+      instances: 1,
+      node_args: ['--require', REQUIRE_SCRIPT],
+      env: {
+        PM2_TEST_REQUIRE_VAR: 'cluster-env-value',
+        PM2_REQUIRE_RESULT_FILE: CLUSTER_RESULT
+      }
+    }, function (err) {
+      should(err).be.null()
+
+      setTimeout(function () {
+        var data = JSON.parse(fs.readFileSync(CLUSTER_RESULT, 'utf8'))
+        data.value.should.eql(
+          'cluster-env-value',
+          'PM2_TEST_REQUIRE_VAR should be visible in --require script running in cluster mode'
+        )
+        done()
+      }, 3000)
+    })
+  })
+
+  it('should expose PM2 env vars to --require scripts in fork mode', function (done) {
+    PM2.start({
+      script: './../fixtures/empty.js',
+      name: 'test-require-env-fork',
+      exec_mode: 'fork',
+      node_args: ['--require', REQUIRE_SCRIPT],
+      env: {
+        PM2_TEST_REQUIRE_VAR: 'fork-env-value',
+        PM2_REQUIRE_RESULT_FILE: FORK_RESULT
+      }
+    }, function (err) {
+      should(err).be.null()
+
+      setTimeout(function () {
+        var data = JSON.parse(fs.readFileSync(FORK_RESULT, 'utf8'))
+        data.value.should.eql(
+          'fork-env-value',
+          'PM2_TEST_REQUIRE_VAR should be visible in --require script running in fork mode'
+        )
+        done()
+      }, 3000)
+    })
+  })
+})
diff --git a/test/unit.sh b/test/unit.sh
index 0dfb53324..32c201f90 100644
--- a/test/unit.sh
+++ b/test/unit.sh
@@ -100,6 +100,7 @@ runUnitTest $D/issue_5990_bun_substring_match.mocha.js
 runUnitTest $D/issue_6089_prototype_pollution.mocha.js
 runUnitTest $D/issue_6075_redos.mocha.js
 runUnitTest $D/issue_6073_object_env.mocha.js
+runUnitTest $D/require_cluster_env.mocha.js
 runUnitTest $D/treekill.mocha.js
 runUnitTest $D/http_interface.mocha.js