diff --git a/setup.py b/setup.py
index ca3184f..8dc9e71 100644
--- a/setup.py
+++ b/setup.py
@@ -23,6 +23,10 @@
     'six>=1.9.0',
 )
 
+EXTRA_OAUTHLIB_DEPENDENCIES = (
+    'requests-oauthlib>=0.7.0',
+)
+
 
 with open('README.rst', 'r') as fh:
     long_description = fh.read()
@@ -38,6 +42,9 @@
     packages=find_packages(exclude=('tests', 'system_tests')),
     namespace_packages=('google',),
     install_requires=DEPENDENCIES,
+    extras_require={
+        'oauthlib': EXTRA_OAUTHLIB_DEPENDENCIES,
+    },
     license='Apache 2.0',
     keywords='google auth oauth client',
     classifiers=(