diff --git a/CHANGES.md b/CHANGES.md
index d13dcb717..f25c7d0c1 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,3 +1,18 @@
+Synapse 1.3.1 (2019-08-17)
+==========================
+
+Features
+--------
+
+- Drop hard dependency on `sdnotify` python package. ([\#5871](https://github.com/matrix-org/synapse/issues/5871))
+
+
+Bugfixes
+--------
+
+- Fix startup issue (hang on ACME provisioning) due to ordering of Twisted reactor startup. Thanks to @chrismoos for supplying the fix. ([\#5867](https://github.com/matrix-org/synapse/issues/5867))
+
+
 Synapse 1.3.0 (2019-08-15)
 ==========================
 
diff --git a/debian/changelog b/debian/changelog
index 83232a0ba..76efc442d 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,8 +1,19 @@
+matrix-synapse-py3 (1.3.1) stable; urgency=medium
+
+  * New synapse release 1.3.1.
+
+ -- Synapse Packaging team <packages@matrix.org>  Sat, 17 Aug 2019 09:15:49 +0100
+
 matrix-synapse-py3 (1.3.0) stable; urgency=medium
 
   [ Andrew Morgan ]
   * Remove libsqlite3-dev from required build dependencies.
 
+  [ Synapse Packaging team ]
+  * New synapse release 1.3.0.
+
+ -- Synapse Packaging team <packages@matrix.org>  Thu, 15 Aug 2019 12:04:23 +0100
+
 matrix-synapse-py3 (1.2.0) stable; urgency=medium
 
   [ Amber Brown ]
@@ -13,9 +24,8 @@ matrix-synapse-py3 (1.2.0) stable; urgency=medium
 
   [ Synapse Packaging team ]
   * New synapse release 1.2.0.
-  * New synapse release 1.3.0.
 
- -- Synapse Packaging team <packages@matrix.org>  Thu, 15 Aug 2019 12:04:23 +0100
+ -- Synapse Packaging team <packages@matrix.org>  Thu, 25 Jul 2019 14:10:07 +0100
 
 matrix-synapse-py3 (1.1.0) stable; urgency=medium
 
diff --git a/synapse/__init__.py b/synapse/__init__.py
index 02ae90b07..6766ef445 100644
--- a/synapse/__init__.py
+++ b/synapse/__init__.py
@@ -35,4 +35,4 @@ try:
 except ImportError:
     pass
 
-__version__ = "1.3.0"
+__version__ = "1.3.1"
diff --git a/synapse/app/_base.py b/synapse/app/_base.py
index c010e7095..69dcf3523 100644
--- a/synapse/app/_base.py
+++ b/synapse/app/_base.py
@@ -17,10 +17,10 @@ import gc
 import logging
 import os
 import signal
+import socket
 import sys
 import traceback
 
-import sdnotify
 from daemonize import Daemonize
 
 from twisted.internet import defer, error, reactor
@@ -246,13 +246,12 @@ def start(hs, listeners=None):
             def handle_sighup(*args, **kwargs):
                 # Tell systemd our state, if we're using it. This will silently fail if
                 # we're not using systemd.
-                sd_channel = sdnotify.SystemdNotifier()
-                sd_channel.notify("RELOADING=1")
+                sdnotify(b"RELOADING=1")
 
                 for i in _sighup_callbacks:
                     i(hs)
 
-                sd_channel.notify("READY=1")
+                sdnotify(b"READY=1")
 
             signal.signal(signal.SIGHUP, handle_sighup)
 
@@ -308,16 +307,12 @@ def setup_sdnotify(hs):
 
     # Tell systemd our state, if we're using it. This will silently fail if
     # we're not using systemd.
-    sd_channel = sdnotify.SystemdNotifier()
-
     hs.get_reactor().addSystemEventTrigger(
-        "after",
-        "startup",
-        lambda: sd_channel.notify("READY=1\nMAINPID=%s" % (os.getpid())),
+        "after", "startup", sdnotify, b"READY=1\nMAINPID=%i" % (os.getpid(),)
     )
 
     hs.get_reactor().addSystemEventTrigger(
-        "before", "shutdown", lambda: sd_channel.notify("STOPPING=1")
+        "before", "shutdown", sdnotify, b"STOPPING=1"
     )
 
 
@@ -414,3 +409,35 @@ class _DeferredResolutionReceiver(object):
     def resolutionComplete(self):
         self._deferred.callback(())
         self._receiver.resolutionComplete()
+
+
+sdnotify_sockaddr = os.getenv("NOTIFY_SOCKET")
+
+
+def sdnotify(state):
+    """
+    Send a notification to systemd, if the NOTIFY_SOCKET env var is set.
+
+    This function is based on the sdnotify python package, but since it's only a few
+    lines of code, it's easier to duplicate it here than to add a dependency on a
+    package which many OSes don't include as a matter of principle.
+
+    Args:
+        state (bytes): notification to send
+    """
+    if not isinstance(state, bytes):
+        raise TypeError("sdnotify should be called with a bytes")
+    if not sdnotify_sockaddr:
+        return
+    addr = sdnotify_sockaddr
+    if addr[0] == "@":
+        addr = "\0" + addr[1:]
+
+    try:
+        with socket.socket(socket.AF_UNIX, socket.SOCK_DGRAM) as sock:
+            sock.connect(addr)
+            sock.sendall(state)
+    except Exception as e:
+        # this is a bit surprising, since we don't expect to have a NOTIFY_SOCKET
+        # unless systemd is expecting us to notify it.
+        logger.warning("Unable to send notification to systemd: %s", e)
diff --git a/synapse/app/homeserver.py b/synapse/app/homeserver.py
index 7d6b51b5b..823390584 100644
--- a/synapse/app/homeserver.py
+++ b/synapse/app/homeserver.py
@@ -447,7 +447,7 @@ def setup(config_options):
                 reactor.stop()
             sys.exit(1)
 
-    reactor.addSystemEventTrigger("before", "startup", start)
+    reactor.callWhenRunning(start)
 
     return hs
 
diff --git a/synapse/python_dependencies.py b/synapse/python_dependencies.py
index 195a7a70c..c6465c038 100644
--- a/synapse/python_dependencies.py
+++ b/synapse/python_dependencies.py
@@ -72,7 +72,6 @@ REQUIREMENTS = [
     "netaddr>=0.7.18",
     "Jinja2>=2.9",
     "bleach>=1.4.3",
-    "sdnotify>=0.3",
 ]
 
 CONDITIONAL_REQUIREMENTS = {