diff --git a/lib/provider.js b/lib/provider.js
index c428b834..20dd6448 100644
--- a/lib/provider.js
+++ b/lib/provider.js
@@ -2,11 +2,11 @@ var path = require('path')
 var fork = require('child_process').fork
 
 var adb = require('adbkit')
-var async = require('async')
+var Q = require('q')
 
 var log = require('./util/logger').createLogger('provider')
 var client = adb.createClient()
-var workers = {}
+var workers = Object.create(null)
 
 client.trackDevices(function(err, tracker) {
   if (err) {
@@ -96,30 +96,62 @@ function maybeDisconnect(device) {
   return false
 }
 
-function gracefullyKillWorker(id, done) {
-  var proc = workers[id].proc
-    , timer
-
-  timer = setTimeout(function() {
-    log.error('Device worker "%s" did not stop in time', id)
-    proc.removeListener('exit', onExit)
-    log.warn('Force killing worker of device "%s"', id)
-    proc.kill('SIGKILL')
-    done()
-  }, 10000)
+function tryKillWorker(id) {
+  var deferred = Q.defer(),
+      worker = workers[id]
 
   function onExit() {
-    clearTimeout(timer)
-    done()
+    deferred.resolve()
   }
 
-  proc.once('exit', onExit)
-  proc.kill('SIGTERM')
+  worker.proc.once('exit', onExit)
+  worker.proc.kill('SIGTERM')
+
+  return deferred.promise.finally(function() {
+    worker.proc.removeListener('exit', onExit)
+  })
+}
+
+function forceKillWorker(id) {
+  log.warn('Force killing worker of device "%s"', id)
+
+  var deferred = Q.defer()
+    , worker = workers[id]
+
+  function onExit() {
+    deferred.resolve()
+  }
+
+  worker.proc.once('exit', onExit)
+  worker.proc.kill('SIGKILL')
+
+  return deferred.promise.finally(function() {
+    worker.proc.removeListener('exit', onExit)
+  })
+}
+
+function gracefullyKillWorker(id) {
+  var deferred = Q.defer()
+
+  tryKillWorker(id)
+    .timeout(10000)
+    .then(deferred.resolve)
+    .catch(function() {
+      log.error('Device worker "%s" did not stop in time', id)
+      forceKillWorker(id).then(deferred.resolve)
+    })
+
+  return deferred.promise
 }
 
 function gracefullyExit() {
   log.info('Stopping all workers')
-  async.each(Object.keys(workers), gracefullyKillWorker, function(err) {
+  Q.spawn(function* foo() {
+    var ops = []
+    for (var id in workers) {
+      ops.push(gracefullyKillWorker(id))
+    }
+    yield Q.all(ops)
     log.info('All cleaned up')
     process.exit(0)
   })