diff --git a/.travis.yml b/.travis.yml
index a513a5e2..abdf98a4 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -40,6 +40,10 @@ jobs:
       dist: xenial
       sudo: true
       env: TACKPY=false
+    - python: 3.9
+      dist: xenial
+      sudo: true
+      env: TACKPY=false
     - python: 2.7
       env: TACKPY=true
     - python: 3.4
diff --git a/setup.py b/setup.py
index dc5034cb..32df1a00 100755
--- a/setup.py
+++ b/setup.py
@@ -40,6 +40,7 @@
             'Programming Language :: Python :: 3.6',
             'Programming Language :: Python :: 3.7',
             'Programming Language :: Python :: 3.8',
+            'Programming Language :: Python :: 3.9',
             'Topic :: Security :: Cryptography',
             'Topic :: Software Development :: Libraries :: Python Modules',
             'Topic :: System :: Networking'
diff --git a/tlslite/integration/imap4_tls.py b/tlslite/integration/imap4_tls.py
index 3254b543..272b7f75 100644
--- a/tlslite/integration/imap4_tls.py
+++ b/tlslite/integration/imap4_tls.py
@@ -82,8 +82,10 @@ def __init__(self, host = '', port = IMAP4_TLS_PORT,
 
         IMAP4.__init__(self, host, port)
 
-
-    def open(self, host = '', port = IMAP4_TLS_PORT):
+    # the `timeout` is a new argument in python3.9, so checks with
+    # older python versions will complain about unmatched parameters
+    # pylint: disable=arguments-differ
+    def open(self, host='', port=IMAP4_TLS_PORT, timeout=None):
         """Setup connection to remote server on "host:port".
 
         This connection will be used by the routines:
@@ -96,3 +98,4 @@ def open(self, host = '', port = IMAP4_TLS_PORT):
         self.sock = TLSConnection(self.sock)
         ClientHelper._handshake(self, self.sock)
         self.file = self.sock.makefile('rb')
+    # pylint: enable=arguments-differ