diff --git a/.travis.yml b/.travis.yml
index 7424bc4e..4f073aab 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -7,6 +7,8 @@ python:
 - '3.4'
 - '3.5'
 install:
+# ensure we have recent pip/setuptools
+- pip install --upgrade pip setuptools
 - pip install -r requirements-test.txt
 - pip install release-manager
 - pip install -e .
diff --git a/setup.py b/setup.py
index 88392f47..cafd4581 100644
--- a/setup.py
+++ b/setup.py
@@ -75,12 +75,12 @@
     ],
 
     install_requires=[
-        "greenlet==0.4.10",
-        "requests==2.2.1",
+        "greenlet>=0.4.10",
+        "requests>=2.2.1",
         "pycontracts==1.7.6",
-        "celery==3.1.11",
-        "gevent==1.0.2",
-        "redis==2.9.1",
-        "six==1.9.0"
+        "celery>=3.1.11,<3.1.25",
+        "gevent>=1.0.2",
+        "redis>=2.9.1",
+        "six>=1.9.0"
     ],
 )
diff --git a/snowplow_tracker/emitters.py b/snowplow_tracker/emitters.py
index 2eccb0fb..450c0875 100644
--- a/snowplow_tracker/emitters.py
+++ b/snowplow_tracker/emitters.py
@@ -31,7 +31,6 @@
     from queue import Queue
 
 from celery import Celery
-from celery.contrib.methods import task
 import redis
 import requests
 from contracts import contract, new_contract
@@ -172,7 +171,7 @@ def reached_limit(self):
         else:
             return self.bytes_queued >= self.byte_limit or len(self.buffer) >= self.buffer_size
 
-    @task(name="Flush")
+    @app.task(name="Flush")
     def flush(self):
         """
             Sends all events in the buffer to the collector.
@@ -393,16 +392,32 @@ class CeleryEmitter(Emitter):
         Works like the base Emitter class,
         but on_success and on_failure callbacks cannot be set.
     """
+    celery_app = None
+
     def __init__(self, endpoint, protocol="http", port=None, method="get", buffer_size=None, byte_limit=None):
         super(CeleryEmitter, self).__init__(endpoint, protocol, port, method, buffer_size, None, None, byte_limit)
 
+        try:
+            # Check whether a custom Celery configuration module named "snowplow_celery_config" exists
+            import snowplow_celery_config
+            self.celery_app = Celery()
+            self.celery_app.config_from_object(snowplow_celery_config)
+        except ImportError:
+            # Otherwise configure Celery with default settings
+            self.celery_app = Celery("Snowplow", broker="redis://guest@localhost//")
+
+        self.async_flush_task = self.celery_app.task(self.async_flush)
+
     def flush(self):
         """
             Schedules a flush task
         """
-        super(CeleryEmitter, self).flush.delay()
+        self.async_flush_task.delay()
         logger.info("Scheduled a Celery task to flush the event queue")
 
+    def async_flush(self):
+        super(CeleryEmitter, self).flush()
+
 
 class RedisEmitter(object):
     """
diff --git a/snowplow_tracker/tracker.py b/snowplow_tracker/tracker.py
index a6830a68..058fa2b6 100644
--- a/snowplow_tracker/tracker.py
+++ b/snowplow_tracker/tracker.py
@@ -626,16 +626,16 @@ def track_unstruct_event(self, event_json, context=None, tstamp=None):
     track_self_describing_event = track_unstruct_event
 
     @contract
-    def flush(self, async=False):
+    def flush(self, asynchronously=False):
         """
             Flush the emitter
 
-            :param  async:  Whether the flush is done asynchronously. Default is False
-            :type   async:  bool
+            :param  asynchronously:  Whether the flush is done asynchronously. Default is False
+            :type   asynchronously:  bool
             :rtype:         tracker
         """
         for emitter in self.emitters:
-            if async:
+            if asynchronously:
                 emitter.flush()
             else:
                 emitter.sync_flush()