diff --git a/tests/unit/http/test_http_client.py b/tests/unit/http/test_http_client.py
index a61326bcf7..6db824c0ef 100644
--- a/tests/unit/http/test_http_client.py
+++ b/tests/unit/http/test_http_client.py
@@ -1,5 +1,7 @@
 # -*- coding: utf-8 -*-
 import unittest
+import os
+from collections import OrderedDict
 
 from mock import patch, Mock
 from requests import Session
@@ -137,17 +139,37 @@ def test_last_response_empty_on_error(self):
             self.assertIsNone(self.client.last_response)
 
     def test_request_behind_proxy(self):
-        proxies = {
-            'http': 'http://proxy.twilio.com',
-            'https': 'https://proxy.twilio.com',
-        }
+        self.request_mock.url = 'https://api.twilio.com/'
+        proxies = OrderedDict([
+            ('http', 'http://proxy.twilio.com'),
+            ('https', 'https://proxy.twilio.com'),
+        ])
         self.client = TwilioHttpClient(proxy=proxies)
         self.client.request('doesnt matter', 'doesnt matter')
-        self.assertEqual(proxies, self.session_mock.proxies)
+        self.session_mock.send.assert_called_once_with(
+            self.request_mock, verify=True, proxies=proxies, stream=False,
+            cert=None, allow_redirects=False, timeout=None
+        )
+
+    @patch.dict(os.environ, {
+        "HTTP_PROXY": "http://proxy.twilio.com",
+        "HTTPS_PROXY": "https://proxy.twilio.com"
+    })
+    def test_request_behind_proxy_from_environment(self):
+        self.request_mock.url = 'https://api.twilio.com/'
+        self.client = TwilioHttpClient()
+        self.client.request('doesnt matter', 'doesnt matter')
+        self.session_mock.send.assert_called_once_with(
+            self.request_mock, verify=True, proxies=OrderedDict([
+                ('http', 'http://proxy.twilio.com'),
+                ('https', 'https://proxy.twilio.com'),
+            ]), stream=False, cert=None, allow_redirects=False, timeout=None
+        )
 
     def test_exception_with_details(self):
+        self.request_mock.url = 'https://api.twilio.com/'
         v1 = MyVersion(self.client)
-        error_text = """{   
+        error_text = """{
             "code": 20001,
             "message": "Bad request",
             "more_info": "https://www.twilio.com/docs/errors/20001",
@@ -179,7 +201,7 @@ def tearDown(self):
 
     def _setup_session_response(self, value):
         session_mock = Mock(wraps=Session())
-        request_mock = Mock()
+        request_mock = Mock(url='https://api.twilio.com/')
 
         session_mock.prepare_request.return_value = request_mock
         session_mock.send.return_value = Response(200, value)
diff --git a/twilio/http/http_client.py b/twilio/http/http_client.py
index a9ce024a2a..320bdafe12 100644
--- a/twilio/http/http_client.py
+++ b/twilio/http/http_client.py
@@ -39,7 +39,7 @@ def __init__(self, pool_connections=True, request_hooks=None, timeout=None, logg
         if timeout is not None and timeout <= 0:
             raise ValueError(timeout)
         self.timeout = timeout
-        self.proxy = proxy
+        self.proxy = proxy if proxy else {}
 
     def request(self, method, url, params=None, data=None, headers=None, auth=None, timeout=None,
                 allow_redirects=False):
@@ -82,17 +82,17 @@ def request(self, method, url, params=None, data=None, headers=None, auth=None,
 
         self.last_response = None
         session = self.session or Session()
-        if self.proxy:
-            session.proxies = self.proxy
         request = Request(**kwargs)
         self.last_request = TwilioRequest(**kwargs)
 
         prepped_request = session.prepare_request(request)
-        response = session.send(
-            prepped_request,
-            allow_redirects=allow_redirects,
-            timeout=timeout if timeout is not None else self.timeout,
-        )
+
+        settings = session.merge_environment_settings(prepped_request.url, self.proxy, None, None, None)
+
+        settings['allow_redirects'] = allow_redirects
+        settings['timeout'] = timeout if timeout is not None else self.timeout
+
+        response = session.send(prepped_request, **settings)
 
         self.logger.info('{method} Response: {status} {text}'.format(
             method=method, status=response.status_code, text=response.text)