diff --git a/celerytest/__init__.py b/celerytest/__init__.py
index 9607ff5..52b74a6 100644
--- a/celerytest/__init__.py
+++ b/celerytest/__init__.py
@@ -1,9 +1,10 @@
-from config import CELERY_TEST_CONFIG, CELERY_TEST_CONFIG_MEMORY
-from worker import CeleryWorkerThread
+from .config import CELERY_TEST_CONFIG, CELERY_TEST_CONFIG_MEMORY
+from .worker import CeleryWorkerThread
 
 
 def setup_celery_worker(app, config=CELERY_TEST_CONFIG_MEMORY, concurrency=1):
-    conf = dict(CELERY_TEST_CONFIG.__dict__.items() + config.__dict__.items())
+    conf = dict(CELERY_TEST_CONFIG.__dict__.items())
+    conf.update(config.__dict__.items())
     conf['CELERYD_CONCURRENCY'] = concurrency
     app.config_from_object(conf)
 
diff --git a/celerytest/tests.py b/celerytest/tests.py
index 7fc4e22..0aabd8f 100644
--- a/celerytest/tests.py
+++ b/celerytest/tests.py
@@ -98,4 +98,9 @@ def test_scheduled_task(self):
         t5 = time.time()
         self.assertTrue(result.ready())
 
-        self.assertTrue(t5-t4 < self.overhead_time)
\ No newline at end of file
+        self.assertTrue(t5-t4 < self.overhead_time)
+
+    def test_wait_for_idle(self):
+        result = multiply.delay(2, 3)
+        self.worker.idle.wait()
+        self.assertTrue(result.ready())
diff --git a/celerytest/worker.py b/celerytest/worker.py
index 9000118..979eea9 100644
--- a/celerytest/worker.py
+++ b/celerytest/worker.py
@@ -17,6 +17,8 @@ def __init__(self, app):
         self.workers = []
         self.consumers = []
         self.monitor = CeleryMonitorThread(app)
+        signals.after_task_publish.connect(self.monitor.task_begin)
+        signals.task_postrun.connect(self.monitor.task_finished)
 
         self.ready = threading.Event()
         self.active = self.monitor.active
@@ -77,28 +79,28 @@ def __init__(self, app):
         self.stop_requested = False
 
         self.pending = 0
+        self.pending_lock = threading.Lock()
         self.idle = threading.Event()
         self.idle.set()
         self.active = threading.Event()
 
-    def on_event(self, event):
-        # maintain state
-        self.state.event(event)
 
-        # only need to update state when something relevant to pending tasks is happening
-        check_states = ['task-received','task-started','task-succeeded','task-failed','task-revoked']
-        if not event['type'] in check_states:
-            return
-
-        active = len(self.immediate_pending_tasks) > 0
-        
-        # switch signals if needed
-        if active and self.idle.is_set():
+    def task_begin(self, *args, **kwargs):
+        with self.pending_lock:
+            self.pending += 1
             self.idle.clear()
             self.active.set()
-        elif not active and self.active.is_set():
-            self.idle.set()
-            self.active.clear()
+
+    def task_finished(self, *args, **kwargs):
+        with self.pending_lock:
+            self.pending -= 1
+            if self.pending <= 0:
+                self.active.clear()
+                self.idle.set()
+
+    def on_event(self, event):
+        # maintain state
+        self.state.event(event)
 
     @property
     def pending_tasks(self):