diff --git a/pkgs/development/python-modules/MechanicalSoup/default.nix b/pkgs/development/python-modules/MechanicalSoup/default.nix
index 56e2cf501eda..b5d202af50a4 100644
--- a/pkgs/development/python-modules/MechanicalSoup/default.nix
+++ b/pkgs/development/python-modules/MechanicalSoup/default.nix
@@ -1,5 +1,5 @@
 { fetchPypi, buildPythonPackage, lib
-, requests, beautifulsoup4, six
+, requests, beautifulsoup4, six, lxml
 , pytestrunner, requests-mock, pytestcov, pytest
 }:
 
@@ -7,23 +7,23 @@
 buildPythonPackage rec {
   name = "${pname}-${version}";
   pname = "MechanicalSoup";
-  version = "0.8.0";
+  version = "0.9.0.post4";
 
   src = fetchPypi {
     inherit pname version;
-    sha256 = "38a6ca35428196be94f87f8f036ee4a88b1418d1f77e5634ad92acfaa22c28da";
+    sha256 = "ce8f822afbc9bef1499be417e8d5deecd0cd32606420165700e89477955f03ab";
   };
 
   checkInputs = [ pytest pytestrunner requests-mock pytestcov ];
 
-  propagatedBuildInputs = [ requests beautifulsoup4 six ];
+  propagatedBuildInputs = [ lxml requests beautifulsoup4 six ];
 
   # Requires network
   doCheck = false;
 
   postPatch = ''
     # Is in setup_requires but not used in setup.py...
-    substituteInPlace setup.py --replace "'pytest-runner'," ""
+    substituteInPlace setup.py --replace "'pytest-runner'" ""
   '';
 
   meta = with lib; {