diff --git a/.travis.yml b/.travis.yml
index e5ef98c..e10d016 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,12 +1,13 @@
 language: python
 
+os: linux
+dist: xenial
+
 python:
-  - "2.6"
   - "2.7"
-  - "3.3"
-  - "3.4"
   - "3.5"
   - "3.6"
+  - "3.7"
 
 install:
   - pip install -U pip setuptools
diff --git a/requests_ntlm/requests_ntlm.py b/requests_ntlm/requests_ntlm.py
index 23db0cc..a253607 100644
--- a/requests_ntlm/requests_ntlm.py
+++ b/requests_ntlm/requests_ntlm.py
@@ -1,3 +1,4 @@
+import base64
 import binascii
 import sys
 import warnings
@@ -71,8 +72,12 @@ def retry_using_http_NTLM_auth(self, auth_header_field, auth_header,
 
         # ntlm returns the headers as a base64 encoded bytestring. Convert to
         # a string.
-        context = ntlm.Ntlm()
-        negotiate_message = context.create_negotiate_message(self.domain).decode('ascii')
+        context = ntlm.NtlmContext(
+            username=self.username,
+            password=self.password,
+            domain=self.domain or None,
+        )
+        negotiate_message = base64.b64encode(context.step()).decode('ascii')
         auth = u'%s %s' % (auth_type, negotiate_message)
         request.headers[auth_header] = auth
 
@@ -110,17 +115,12 @@ def retry_using_http_NTLM_auth(self, auth_header_field, auth_header,
         ).strip()
 
         # Parse the challenge in the ntlm context
-        context.parse_challenge_message(ntlm_header_value[len(auth_strip):])
+        challenge_token = base64.b64decode(ntlm_header_value[len(auth_strip):])
 
         # build response
         # Get the response based on the challenge message
-        authenticate_message = context.create_authenticate_message(
-            self.username,
-            self.password,
-            self.domain,
-            server_certificate_hash=server_certificate_hash
-        )
-        authenticate_message = authenticate_message.decode('ascii')
+        context._server_certificate_hash = server_certificate_hash
+        authenticate_message = base64.b64encode(context.step(challenge_token)).decode('ascii')
         auth = u'%s %s' % (auth_type, authenticate_message)
         request.headers[auth_header] = auth
 
@@ -131,7 +131,7 @@ def retry_using_http_NTLM_auth(self, auth_header_field, auth_header,
         response3.history.append(response2)
 
         # Get the session_security object created by ntlm-auth for signing and sealing of messages
-        self.session_security = context.session_security
+        self.session_security = context._session_security
 
         return response3
 
diff --git a/requirements.txt b/requirements.txt
index ede853a..b396b6f 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,7 +1,7 @@
 requests>=2.0.0
-ntlm-auth>=1.0.2
+ntlm-auth>=1.2.0
 cryptography>=1.3
 flask
 pytest
-pytest-cov
+pytest-cov<2.6
 wheel
diff --git a/setup.py b/setup.py
index d7c6e0b..fff258a 100644
--- a/setup.py
+++ b/setup.py
@@ -7,7 +7,7 @@
     name='requests_ntlm',
     version='1.1.0',
     packages=[ 'requests_ntlm' ],
-    install_requires=[ 'requests>=2.0.0', 'ntlm-auth>=1.0.2', 'cryptography>=1.3' ],
+    install_requires=[ 'requests>=2.0.0', 'ntlm-auth>=1.2.0', 'cryptography>=1.3' ],
     provides=[ 'requests_ntlm' ],
     author='Ben Toews',
     author_email='mastahyeti@gmail.com',