diff --git a/googleapiclient/channel.py b/googleapiclient/channel.py
index 702186b..7d0feb9 100644
--- a/googleapiclient/channel.py
+++ b/googleapiclient/channel.py
@@ -64,6 +64,13 @@
 from oauth2client import util
 import six
 
+# Oauth2client < 3 has the positional helper in 'util', >= 3 has it
+# in '_helpers'.
+try:
+  from oauth2client import util
+except ImportError:
+  from oauth2client import _helpers as util
+
 
 # The unix time epoch starts at midnight 1970.
 EPOCH = datetime.datetime.utcfromtimestamp(0)
diff --git a/googleapiclient/discovery.py b/googleapiclient/discovery.py
index ecb75fa..8609e3a 100644
--- a/googleapiclient/discovery.py
+++ b/googleapiclient/discovery.py
@@ -69,8 +69,15 @@
 from googleapiclient.model import RawModel
 from googleapiclient.schema import Schemas
 from oauth2client.client import GoogleCredentials
-from oauth2client.util import _add_query_parameter
-from oauth2client.util import positional
+
+# Oauth2client < 3 has the positional helper in 'util', >= 3 has it
+# in '_helpers'.
+try:
+  from oauth2client.util import _add_query_parameter
+  from oauth2client.util import positional
+except ImportError:
+  from oauth2client._helpers import _add_query_parameter
+  from oauth2client._helpers import positional
 
 
 # The client library requires a version of httplib2 that supports RETRIES.
diff --git a/googleapiclient/errors.py b/googleapiclient/errors.py
index 3d44de7..1b79d2f 100644
--- a/googleapiclient/errors.py
+++ b/googleapiclient/errors.py
@@ -23,7 +23,12 @@
 
 import json
 
-from oauth2client import util
+# Oauth2client < 3 has the positional helper in 'util', >= 3 has it
+# in '_helpers'.
+try:
+  from oauth2client import util
+except ImportError:
+  from oauth2client import _helpers as util
 
 
 class Error(Exception):
diff --git a/googleapiclient/http.py b/googleapiclient/http.py
index 1e168c1..14580f0 100644
--- a/googleapiclient/http.py
+++ b/googleapiclient/http.py
@@ -55,6 +55,13 @@
 from email.mime.nonmultipart import MIMENonMultipart
 from email.parser import FeedParser
 
+# Oauth2client < 3 has the positional helper in 'util', >= 3 has it
+# in '_helpers'.
+try:
+  from oauth2client import util
+except ImportError:
+  from oauth2client import _helpers as util
+
 from googleapiclient import mimeparse
 from googleapiclient.errors import BatchError
 from googleapiclient.errors import HttpError
@@ -63,7 +70,6 @@
 from googleapiclient.errors import UnexpectedBodyError
 from googleapiclient.errors import UnexpectedMethodError
 from googleapiclient.model import JsonModel
-from oauth2client import util
 
 
 LOGGER = logging.getLogger(__name__)
diff --git a/googleapiclient/schema.py b/googleapiclient/schema.py
index ecb3f8b..9feaf28 100644
--- a/googleapiclient/schema.py
+++ b/googleapiclient/schema.py
@@ -65,7 +65,12 @@
 
 import copy
 
-from oauth2client import util
+# Oauth2client < 3 has the positional helper in 'util', >= 3 has it
+# in '_helpers'.
+try:
+  from oauth2client import util
+except ImportError:
+  from oauth2client import _helpers as util
 
 
 class Schemas(object):
diff --git a/setup.py b/setup.py
index 7dd6a0a..b4edba6 100644
--- a/setup.py
+++ b/setup.py
@@ -64,7 +64,7 @@
 
 install_requires = [
     'httplib2>=0.8,<1',
-    'oauth2client',
+    'oauth2client>=1.5.0,<4.0.0',
     'six>=1.6.1,<2',
     'uritemplate>=0.6,<1',
 ]
diff --git a/tox.ini b/tox.ini
index 44f21da..a87dad3 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,10 +1,11 @@
 [tox]
-envlist = py{26,27,33,34}-oauth2client{1,2}
+envlist = py{26,27,33,34}-oauth2client{1,2,3}
 
 [testenv]
 deps =
        oauth2client1: oauth2client<2
        oauth2client2: oauth2client>=2,<=3
+       oauth2client3: oauth2client>=3,<=4
        keyring
        mox
        pyopenssl