diff --git a/lib/cli.mjs b/lib/cli.mjs
index 01e83ab..98cd88f 100644
--- a/lib/cli.mjs
+++ b/lib/cli.mjs
@@ -3,6 +3,7 @@ import fs from 'fs'
 import fsPromise from 'fs/promises'
 import cluster from 'cluster'
 import child_process from 'child_process'
+import kill from './kill.mjs'
 import Watcher, { EVENT_REMOVE, EVENT_UPDATE } from './watch/index.mjs'
 
 export const MESSAGE_FILES_REQUEST = 'message_files_request'
@@ -41,6 +42,7 @@ export function CLI(e, overrides = {}) {
   this.logger = overrides.logger || console
   this.child_process = overrides.child_process || child_process
   this.process = overrides.process || process
+  this.kill = overrides.kill || kill
   this.importer = overrides.importer
   this.loadDefaults()
 }
@@ -287,7 +289,7 @@ CLI.prototype.runProgram = function() {
     if (runningTest) {
       return
     } else {
-      this.worker.kill()
+      this.kill(this.worker.pid)
     }
   }
 
diff --git a/lib/kill.mjs b/lib/kill.mjs
new file mode 100644
index 0000000..e976ffd
--- /dev/null
+++ b/lib/kill.mjs
@@ -0,0 +1,59 @@
+import { promisify } from 'util'
+import { spawn, exec } from 'child_process'
+
+const execPromise = promisify(exec)
+
+export default function kill(pid, signal) {
+  let pids = new Set()
+  let getSpawn = null
+
+  switch (process.platform) {
+    case 'win32':
+      return execPromise('taskkill /pid ' + pid + ' /T /F')
+    case 'darwin':
+      getSpawn = function(parentPid) {
+        return spawn('pgrep', ['-P', parentPid])
+      }
+      break
+    default:
+      getSpawn = function (parentPid) {
+        return spawn('ps', ['-o', 'pid', '--no-headers', '--ppid', parentPid])
+      }
+      break
+  }
+
+  return buildTree(pids, getSpawn, pid)
+    .then(function() {
+      for (let pid of pids) {
+        try {
+          process.kill(pid, signal)
+        } catch (err) {
+          if (err.code !== 'ESRCH') throw err;
+        }
+      }
+    })
+}
+
+function buildTree(allPids, spawnGetChildren, parentPid) {
+  allPids.set(parentPid)
+
+  let ps = spawnGetChildren(parentPid)
+  let data = ''
+  ps.stdout.on('data', function(buf) {
+    data += buf.toString('ascii')
+  })
+
+  return new Promise(function(res) {
+    ps.on('close', function(code) {
+      // Check if we got error code (usually means empty results)
+      if (code !== 0) return res()
+
+      res(Promise.all(
+        allData.match(/\d+/g)
+          .map(Number)
+          .filter(pid => !bla.has(pid))
+          .map(buildTree.bind(this, allPids, spawnGetChildren))
+      ))
+    })
+  })
+}
diff --git a/package.json b/package.json
index 9ac95fd..6f3985a 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "eltro",
-  "version": "1.4.2",
+  "version": "1.4.3",
   "description": "Eltro is a tiny no-dependancy test framework for node",
   "main": "index.mjs",
   "scripts": {
diff --git a/test/cli.test.mjs b/test/cli.test.mjs
index ba7d403..8049567 100644
--- a/test/cli.test.mjs
+++ b/test/cli.test.mjs
@@ -26,8 +26,9 @@ t.describe('CLI', function() {
       const cluster = { c: 3 }
       const process = { d: 4 }
       const importer = { e: 5 }
+      const kill = { f: 6 }
       
-      let cliTest = createSafeCli(eltro, { logger, cluster, process, importer })
+      let cliTest = createSafeCli(eltro, { logger, cluster, process, importer, kill })
       assert.strictEqual(cliTest.reporter, 'list')
       assert.strictEqual(cliTest.ignoreOnly, false)
       assert.strictEqual(cliTest.timeout, 2000)
@@ -43,6 +44,7 @@ t.describe('CLI', function() {
       assert.strictEqual(cliTest.cluster, cluster)
       assert.strictEqual(cliTest.process, process)
       assert.strictEqual(cliTest.importer, importer)
+      assert.strictEqual(cliTest.kill, kill)
     })
   
     t.test('should detect isSlave from cluster', function() {
@@ -913,14 +915,16 @@ t.describe('CLI', function() {
     let testCluster
     let testChildProcess
     let testWorker
+    let testKill
     let cli
 
     t.beforeEach(function() {
+      testKill = stub()
       testProcess = { stdout: { write: stub() }, stderr: { write: stub() } }
-      testWorker = { on: stub(), once: stub(), kill: stub(), send: stub(), stderr: { on: stub() }, stdout: { on: stub() } }
+      testWorker = { on: stub(), once: stub(),  send: stub(), stderr: { on: stub() }, stdout: { on: stub() } }
       testCluster = { fork: stub().returns(testWorker) }
       testChildProcess = { spawn: stub().returns(testWorker) }
-      cli = createSafeCli(null, { cluster: testCluster, child_process: testChildProcess, process: testProcess })
+      cli = createSafeCli(null, { cluster: testCluster, child_process: testChildProcess, process: testProcess, kill: testKill })
     })
 
     t.describe('in test mode', function() {
@@ -984,14 +988,14 @@ t.describe('CLI', function() {
       t.test('multiple calls should cancel', function() {
         cli.runProgram()
   
-        assert.notOk(testWorker.kill.called)
+        assert.notOk(testKill.called)
         assert.ok(testCluster.fork.called)
         testCluster.fork.reset()
   
         cli.runProgram()
   
         assert.notOk(testCluster.fork.called)
-        assert.notOk(testWorker.kill.called)
+        assert.notOk(testKill.called)
       })
     })
 
@@ -1063,16 +1067,19 @@ t.describe('CLI', function() {
       })
   
       t.test('multiple calls should kill', function() {
+        const assertPid = 12345235
+        testWorker.pid = assertPid
         cli.runProgram()
   
-        assert.notOk(testWorker.kill.called)
+        assert.notOk(testKill.called)
         assert.ok(testChildProcess.spawn.called)
         testChildProcess.spawn.reset().returns(testWorker)
   
         cli.runProgram()
   
         assert.ok(testChildProcess.spawn.called)
-        assert.ok(testWorker.kill.called)
+        assert.ok(testKill.called)
+        assert.strictEqual(testKill.firstCall[0], assertPid)
       })
     })
   })