diff --git a/README.rst b/README.rst
index 7429a54..4bfe093 100644
--- a/README.rst
+++ b/README.rst
@@ -8,7 +8,7 @@ ElectrumX - Reimplementation of electrum-server
 ===============================================
 
   :Licence: MIT
-  :Language: Python (>= 3.5.1)
+  :Language: Python (>= 3.5.3)
   :Author: Neil Booth
 
 Getting Started
diff --git a/docs/ENVIRONMENT.rst b/docs/ENVIRONMENT.rst
index 41edcbb..6c35b80 100644
--- a/docs/ENVIRONMENT.rst
+++ b/docs/ENVIRONMENT.rst
@@ -252,9 +252,7 @@ some of this.
 
 * **TOR_PROXY_HOST**
 
-  The host where your Tor proxy is running.  Defaults to *127.0.0.1*.
-  If you use a hostname here rather than an IP address, you must have
-  Python version >= 3.5.3, Python 3.5.2 will **not** work.
+  The host where your Tor proxy is running.  Defaults to *localhost*.
 
   If you are not running a Tor proxy just leave this environment
   variable undefined.
diff --git a/docs/HOWTO.rst b/docs/HOWTO.rst
index 8cbdbbc..7404920 100644
--- a/docs/HOWTO.rst
+++ b/docs/HOWTO.rst
@@ -10,7 +10,8 @@ small - pull requests are welcome.
 ================ ========================
 Package          Notes
 ================ ========================
-Python3          ElectrumX uses asyncio.  Python version >= 3.5 is **required**.
+Python3          ElectrumX uses asyncio.  Python version >= 3.5.3 is
+                 **required**.
 `aiohttp`_       Python library for asynchronous HTTP.  Version >=
                  1.0 required; I am using 1.0.5.
 `pylru`_         Python LRU cache package.  I'm using 1.0.9.
diff --git a/electrumx_server.py b/electrumx_server.py
index dd57f2a..695924d 100755
--- a/electrumx_server.py
+++ b/electrumx_server.py
@@ -13,6 +13,7 @@ import asyncio
 import logging
 import os
 import signal
+import sys
 import traceback
 from functools import partial
 
@@ -28,9 +29,12 @@ SUPPRESS_MESSAGES = [
 
 def main_loop():
     '''Start the server.'''
+    if sys.version_info < (3, 5, 3):
+        raise RuntimeError('Python >= 3.5.3 is required to run ElectrumX')
+
     if os.geteuid() == 0:
-        raise Exception('DO NOT RUN AS ROOT! Create an unpriveleged user '
-                        'account and use that')
+        raise RuntimeError('DO NOT RUN AS ROOT! Create an unpriveleged user '
+                           'account and use that')
 
     loop = asyncio.get_event_loop()
     # loop.set_debug(True)
diff --git a/server/controller.py b/server/controller.py
index e04d13f..c0cbf6b 100644
--- a/server/controller.py
+++ b/server/controller.py
@@ -289,8 +289,7 @@ class Controller(util.LoggedClass):
         if env.tcp_port is not None:
             await self.start_server('TCP', env.host, env.tcp_port)
         if env.ssl_port is not None:
-            # Python 3.5.3: use PROTOCOL_TLS
-            sslc = ssl.SSLContext(ssl.PROTOCOL_SSLv23)
+            sslc = ssl.SSLContext(ssl.PROTOCOL_TLS)
             sslc.load_cert_chain(env.ssl_certfile, keyfile=env.ssl_keyfile)
             await self.start_server('SSL', env.host, env.ssl_port, ssl=sslc)
 
diff --git a/server/env.py b/server/env.py
index 774277c..6b1831d 100644
--- a/server/env.py
+++ b/server/env.py
@@ -51,8 +51,7 @@ class Env(LoggedClass):
         # Peer discovery
         self.peer_discovery = bool(self.default('PEER_DISCOVERY', True))
         self.peer_announce = bool(self.default('PEER_ANNOUNCE', True))
-        # Python 3.5.3 - revert back to localhost?
-        self.tor_proxy_host = self.default('TOR_PROXY_HOST', '127.0.0.1')
+        self.tor_proxy_host = self.default('TOR_PROXY_HOST', 'localhost')
         self.tor_proxy_port = self.integer('TOR_PROXY_PORT', None)
         # The electrum client takes the empty string as unspecified
         self.donation_address = self.default('DONATION_ADDRESS', '')
diff --git a/server/peers.py b/server/peers.py
index 03c955e..8eb8501 100644
--- a/server/peers.py
+++ b/server/peers.py
@@ -475,8 +475,7 @@ class PeerManager(util.LoggedClass):
     def retry_peer(self, peer, port_pairs):
         peer.last_try = time.time()
         kind, port = port_pairs[0]
-        # Python 3.5.3: use PROTOCOL_TLS
-        sslc = ssl.SSLContext(ssl.PROTOCOL_SSLv23) if kind == 'SSL' else None
+        sslc = ssl.SSLContext(ssl.PROTOCOL_TLS) if kind == 'SSL' else None
 
         if peer.is_tor:
             create_connection = self.tor_proxy.create_connection
diff --git a/setup.py b/setup.py
index b152c25..b5376cc 100644
--- a/setup.py
+++ b/setup.py
@@ -6,7 +6,7 @@ setuptools.setup(
     name='electrumx',
     version=VERSION.split()[-1],
     scripts=['electrumx_server.py', 'electrumx_rpc.py'],
-    python_requires='>=3.5',
+    python_requires='>=3.5.3',
     # "irc" package is only required if IRC connectivity is enabled
     # via environment variables, in which case I've tested with 15.0.4
     # "x11_hash" package (1.4) is required to sync DASH network.