diff --git a/tahoe-lafs.nix b/tahoe-lafs.nix
index f9460c420f2e79a5d4daa43736aa7e8c9d95d9a4..de4940d98bc36335c60480aaa0cdff90db3bae01 100644
--- a/tahoe-lafs.nix
+++ b/tahoe-lafs.nix
@@ -1,19 +1,19 @@
-{ fetchFromGitHub, nettools, pythonPackages, buildPythonPackage
-, twisted, foolscap, nevow, simplejson, zfec, pycryptopp, darcsver
-, setuptoolsTrial, setuptoolsDarcs, pycrypto, pyasn1, zope_interface
+{ fetchFromGitHub, nettools, python
+, twisted, foolscap, nevow, zfec
+, setuptoolsTrial, pyasn1, zope_interface
 , service-identity, pyyaml, magic-wormhole, treq, appdirs
-, eliot, autobahn
+, eliot, autobahn, cryptography
 }:
-buildPythonPackage rec {
+python.pkgs.buildPythonPackage rec {
   version = "1.14.0.dev";
   name = "tahoe-lafs-${version}";
   src = fetchFromGitHub {
     owner = "LeastAuthority";
     repo = "tahoe-lafs";
     # HEAD of an integration branch for all of the storage plugin stuff.  Last
-    # updated August 20th 2019.
-    rev = "ba2f31f5f3719c7cf9f621852571e89ab445bf61";
-    sha256 = "02c3zghx1951zw1912c2qf9s7n41wsbz8ld5700myak69nvkh0gs";
+    # updated August 23 2019.
+    rev = "d4b5de2e08e26ad2cc14265a5993be2ecc791d5b";
+    sha256 = "1l2da13w43zzwr1z262zhhq4hq3sha4zrxp7d46zmjn4ya0ixksf";
   };
 
   postPatch = ''
@@ -26,19 +26,25 @@ buildPythonPackage rec {
     do
       sed -i "$i" -e"s/localhost/127.0.0.1/g"
     done
-
-    sed -i 's/"zope.interface.*"/"zope.interface"/' src/allmydata/_auto_deps.py
-    sed -i 's/"pycrypto.*"/"pycrypto"/' src/allmydata/_auto_deps.py
   '';
 
 
-  propagatedBuildInputs = with pythonPackages; [
-    twisted foolscap nevow simplejson zfec pycryptopp darcsver
-    setuptoolsTrial setuptoolsDarcs pycrypto pyasn1 zope_interface
-    service-identity pyyaml magic-wormhole treq appdirs
+  propagatedBuildInputs = with python.pkgs; [
+    twisted foolscap nevow zfec appdirs
+    setuptoolsTrial pyasn1 zope_interface
+    service-identity pyyaml magic-wormhole treq
+
+    eliot autobahn cryptography
+  ];
 
-    eliot autobahn
+  checkInputs = with python.pkgs; [
+    hypothesis
+    testtools
+    fixtures
   ];
 
+  checkPhase = ''
+    ${python}/bin/python -m twisted.trial -j4 allmydata
+  '';
   doCheck = false;
 }