diff --git a/pkgs/development/python-modules/pysaml2/default.nix b/pkgs/development/python-modules/pysaml2/default.nix
index 9d355760333c..c16ae01af0ea 100644
--- a/pkgs/development/python-modules/pysaml2/default.nix
+++ b/pkgs/development/python-modules/pysaml2/default.nix
@@ -89,6 +89,8 @@ buildPythonPackage rec {
   pythonImportsCheck = [ "saml2" ];
 
   meta = with lib; {
+    # https://github.com/IdentityPython/pysaml2/issues/947
+    broken = lib.versionAtLeast xmlschema.version "4.2.0";
     description = "Python implementation of SAML Version 2 Standard";
     homepage = "https://github.com/IdentityPython/pysaml2";
     changelog = "https://github.com/IdentityPython/pysaml2/blob/v${version}/CHANGELOG.md";
diff --git a/pkgs/development/python-modules/xmlschema/default.nix b/pkgs/development/python-modules/xmlschema/default.nix
index be3f1ecb12ec..4997eed9be4e 100644
--- a/pkgs/development/python-modules/xmlschema/default.nix
+++ b/pkgs/development/python-modules/xmlschema/default.nix
@@ -12,7 +12,7 @@
 
 buildPythonPackage rec {
   pname = "xmlschema";
-  version = "4.1.0";
+  version = "4.2.0";
   pyproject = true;
 
   disabled = pythonOlder "3.7";
@@ -21,7 +21,7 @@ buildPythonPackage rec {
     owner = "sissaschool";
     repo = "xmlschema";
     tag = "v${version}";
-    hash = "sha256-3nvl49rlwQpNARmWBSw+faL+yNGqNecokjGGpnaC8a0=";
+    hash = "sha256-zwY0YXMlhQEPdHLPivwE9ZI9XoY9UVFHVLUOYNeq9Ew=";
   };
 
   build-system = [ setuptools ];