diff --git a/pkgs/development/python-modules/pysaml2/default.nix b/pkgs/development/python-modules/pysaml2/default.nix
index 621f703992968..42cf63079fdbf 100644
--- a/pkgs/development/python-modules/pysaml2/default.nix
+++ b/pkgs/development/python-modules/pysaml2/default.nix
@@ -97,5 +97,8 @@ buildPythonPackage rec {
     changelog = "https://github.com/IdentityPython/pysaml2/blob/v${version}/CHANGELOG.md";
     license = licenses.asl20;
     maintainers = [ ];
+    # Does not support pyopenssl above 24.3.0 due to use of a deprecated API,
+    # see https://github.com/IdentityPython/pysaml2/issues/975
+    broken = true;
   };
 }
diff --git a/pkgs/servers/matrix-synapse/default.nix b/pkgs/servers/matrix-synapse/default.nix
index a1f78d9a21585..79b5cdc861a5b 100644
--- a/pkgs/servers/matrix-synapse/default.nix
+++ b/pkgs/servers/matrix-synapse/default.nix
@@ -149,7 +149,7 @@ python3.pkgs.buildPythonApplication rec {
       mock
       parameterized
     ])
-    ++ lib.flatten (lib.attrValues optional-dependencies);
+    ++ builtins.filter (p: !p.meta.broken) (lib.flatten (lib.attrValues optional-dependencies));
 
   doCheck = !stdenv.hostPlatform.isDarwin;