diff --git a/luigi/contrib/s3.py b/luigi/contrib/s3.py
index 9fb21d283f..1ccc438d7c 100644
--- a/luigi/contrib/s3.py
+++ b/luigi/contrib/s3.py
@@ -31,9 +31,6 @@
 import warnings
 from multiprocessing.pool import ThreadPool
 
-import botocore
-from boto3.s3.transfer import TransferConfig
-
 try:
     from urlparse import urlsplit
 except ImportError:
@@ -54,6 +51,13 @@
 
 logger = logging.getLogger('luigi-interface')
 
+try:
+    from boto3.s3.transfer import TransferConfig
+    import botocore
+except ImportError:
+    logger.warning("Loading S3 module without the python package boto3. "
+                   "Will crash at runtime if S3 functionality is used.")
+
 
 # two different ways of marking a directory
 # with a suffix in S3
diff --git a/setup.py b/setup.py
index 0fa21e38a2..ab78784bbf 100644
--- a/setup.py
+++ b/setup.py
@@ -13,7 +13,6 @@
 # the License.
 
 import os
-import sys
 
 from setuptools import setup
 
@@ -41,18 +40,16 @@ def get_static_files(path):
     'tornado>=4.0,<5',
     # https://pagure.io/python-daemon/issue/18
     'python-daemon<2.2.0',
+    'enum34>1.1.0;python_version<"3.4"',
 ]
 
 if os.environ.get('READTHEDOCS', None) == 'True':
     # So that we can build documentation for luigi.db_task_history and luigi.contrib.sqla
     install_requires.append('sqlalchemy')
     # readthedocs don't like python-daemon, see #1342
-    install_requires.remove('python-daemon<3.0')
+    install_requires.remove('python-daemon<2.2.0')
     install_requires.append('sphinx>=1.4.4')  # Value mirrored in doc/conf.py
 
-if sys.version_info < (3, 4):
-    install_requires.append('enum34>1.1.0')
-
 setup(
     name='luigi',
     version='2.7.9',