diff --git a/fixtures/slave.js b/fixtures/slave.js
index c0d0840..823b049 100644
--- a/fixtures/slave.js
+++ b/fixtures/slave.js
@@ -15,7 +15,7 @@ var app = http.createServer(function (req, res) {
     return res.end(process.env.CFORK_ENV_TEST);
   }
   if (req.url === '/worker_index') {
-    return res.end(`worker index: ${process.env.CFORK_WORKER_INDEX}`);
+    return res.end(`slave worker index: ${process.env.CFORK_SLAVE_WORKER_INDEX}, ${process.env.CFORK_SLAVE_WORKER_COUNT}`);
   }
   res.end(req.method + ' ' + req.url);
 }).listen(port);
diff --git a/fixtures/worker.js b/fixtures/worker.js
index a05bc67..8fc59ac 100644
--- a/fixtures/worker.js
+++ b/fixtures/worker.js
@@ -25,7 +25,7 @@ var app = http.createServer(function (req, res) {
     return res.end(process.env.CFORK_ENV_TEST);
   }
   if (req.url === '/worker_index') {
-    return res.end(`worker index: ${process.env.CFORK_WORKER_INDEX}`);
+    return res.end(`worker index: ${process.env.CFORK_WORKER_INDEX}, ${process.env.CFORK_WORKER_COUNT}`);
   }
   res.end(req.method + ' ' + req.url);
 }).listen(port);
diff --git a/index.js b/index.js
index 78721d9..b12821f 100644
--- a/index.js
+++ b/index.js
@@ -169,7 +169,7 @@ function fork(options) {
   });
 
   for (var i = 0; i < count; i++) {
-    const env = { CFORK_WORKER_INDEX: String(i) };
+    const env = { CFORK_WORKER_INDEX: String(i), CFORK_WORKER_COUNT: count };
     newWorker = forkWorker(null, env);
     newWorker._clusterSettings = cluster.settings;
     newWorker._clusterWorkerEnv = env;
@@ -181,7 +181,7 @@ function fork(options) {
     slaves.map(normalizeSlaveConfig)
       .forEach(function(settings, index) {
         if (settings) {
-          const env = { CFORK_WORKER_INDEX: String(count + index) };
+          const env = { CFORK_SLAVE_WORKER_INDEX: String(index), CFORK_SLAVE_WORKER_COUNT: slaves.length };
           newWorker = forkWorker(settings, env);
           newWorker._clusterSettings = settings;
           newWorker._clusterWorkerEnv = env;
diff --git a/test/cfork.test.js b/test/cfork.test.js
index e49e2d0..f6cadf6 100644
--- a/test/cfork.test.js
+++ b/test/cfork.test.js
@@ -93,7 +93,7 @@ describe('test/cfork.test.js', () => {
           resp.statusCode.should.equal(200);
           urllib.request('http://localhost:1985/worker_index', function (err, body, resp) {
             should.ifError(err);
-            body.toString().should.equal('worker index: 4');
+            body.toString().should.equal('slave worker index: 0, 1');
             resp.statusCode.should.equal(200);
             done();
           });
@@ -107,13 +107,13 @@ describe('test/cfork.test.js', () => {
       should.ifError(err);
       const text = body.toString();
       // console.log('%o', text);
-      assert(text === 'worker index: 0' || text === 'worker index: 1'
-        || text === 'worker index: 2' || text === 'worker index: 3', text);
+      assert(text === 'worker index: 0, 4' || text === 'worker index: 1, 4'
+        || text === 'worker index: 2, 4 ' || text === 'worker index: 3, 4', text);
       resp.statusCode.should.equal(200);
       urllib.request('http://localhost:1985/worker_index', function (err, body, resp) {
         should.ifError(err);
         const text = body.toString();
-        assert.equal(text, 'worker index: 4');
+        assert.equal(text, 'slave worker index: 0, 1');
         resp.statusCode.should.equal(200);
         done();
       });