diff --git a/pkgs/applications/graphics/freecad/0001-NIXOS-don-t-ignore-PYTHONPATH.patch b/pkgs/applications/graphics/freecad/0001-NIXOS-don-t-ignore-PYTHONPATH.patch
new file mode 100644
index 000000000000..371da24680e0
--- /dev/null
+++ b/pkgs/applications/graphics/freecad/0001-NIXOS-don-t-ignore-PYTHONPATH.patch
@@ -0,0 +1,60 @@
+From c4f452ef6ae083ed21095313582f6d1bd775cbf3 Mon Sep 17 00:00:00 2001
+From: Andreas Rammhold <andreas@rammhold.de>
+Date: Thu, 2 Nov 2023 17:32:07 +0100
+Subject: [PATCH] NIXOS: don't ignore PYTHONPATH
+
+On NixOS or rather within nixpkgs we provide the runtime Python
+packages via the PYTHONPATH environment variable. FreeCAD tries its
+best to ignore Python environment variables that are being inherited
+from the environment. For Python versions >=3.11 it also tries to
+initialize the interpreter config without any environmental data. We
+have to initialize the configuration *with* the information from the
+environment for our packaging to work.
+
+Upstream has purposely isolated the environments AFAIK and thus
+shouldn't accept this patch (as is). What they might accept (once
+support for older Python versions has been dropped) is removing the
+PYTHONPATH specific putenv calls.
+---
+ src/Base/Interpreter.cpp | 2 +-
+ src/Main/MainGui.cpp     | 3 ---
+ 2 files changed, 1 insertion(+), 4 deletions(-)
+
+diff --git a/src/Base/Interpreter.cpp b/src/Base/Interpreter.cpp
+index 52c47168af..9966bd0013 100644
+--- a/src/Base/Interpreter.cpp
++++ b/src/Base/Interpreter.cpp
+@@ -554,7 +554,7 @@ void initInterpreter(int argc,char *argv[])
+ {
+     PyStatus status;
+     PyConfig config;
+-    PyConfig_InitIsolatedConfig(&config);
++    PyConfig_InitPythonConfig(&config);
+ 
+     status = PyConfig_SetBytesArgv(&config, argc, argv);
+     if (PyStatus_Exception(status)) {
+diff --git a/src/Main/MainGui.cpp b/src/Main/MainGui.cpp
+index 48ae847ef4..28813df383 100644
+--- a/src/Main/MainGui.cpp
++++ b/src/Main/MainGui.cpp
+@@ -112,17 +112,14 @@ int main( int argc, char ** argv )
+     // See https://forum.freecad.org/viewtopic.php?f=18&t=20600
+     // See Gui::Application::runApplication()
+     putenv("LC_NUMERIC=C");
+-    putenv("PYTHONPATH=");
+ #elif defined(FC_OS_MACOSX)
+     (void)QLocale::system();
+-    putenv("PYTHONPATH=");
+ #elif defined(__MINGW32__)
+     const char* mingw_prefix = getenv("MINGW_PREFIX");
+     const char* py_home = getenv("PYTHONHOME");
+     if (!py_home && mingw_prefix)
+         _putenv_s("PYTHONHOME", mingw_prefix);
+ #else
+-    _putenv("PYTHONPATH=");
+     // https://forum.freecad.org/viewtopic.php?f=4&t=18288
+     // https://forum.freecad.org/viewtopic.php?f=3&t=20515
+     const char* fc_py_home = getenv("FC_PYTHONHOME");
+-- 
+2.42.0
+
diff --git a/pkgs/applications/graphics/freecad/default.nix b/pkgs/applications/graphics/freecad/default.nix
index f997f23d43cf..76b2a38320d8 100644
--- a/pkgs/applications/graphics/freecad/default.nix
+++ b/pkgs/applications/graphics/freecad/default.nix
@@ -108,6 +108,10 @@ stdenv.mkDerivation (finalAttrs: {
     qtx11extras
   ];
 
+  patches = [
+    ./0001-NIXOS-don-t-ignore-PYTHONPATH.patch
+  ];
+
   cmakeFlags = [
     "-Wno-dev" # turns off warnings which otherwise makes it hard to see what is going on
     "-DBUILD_FLAT_MESH:BOOL=ON"
@@ -127,10 +131,7 @@ stdenv.mkDerivation (finalAttrs: {
     export NIX_LDFLAGS="-L${gfortran.cc}/lib64 -L${gfortran.cc}/lib $NIX_LDFLAGS";
   '';
 
-  # Their main() removes PYTHONPATH=, and we rely on it.
   preConfigure = ''
-    sed '/putenv("PYTHONPATH/d' -i src/Main/MainGui.cpp
-
     qtWrapperArgs+=(--prefix PYTHONPATH : "$PYTHONPATH")
   '';
 
diff --git a/pkgs/development/python-modules/pyside2/default.nix b/pkgs/development/python-modules/pyside2/default.nix
index 7670b443318b..5dfa7fb823fa 100644
--- a/pkgs/development/python-modules/pyside2/default.nix
+++ b/pkgs/development/python-modules/pyside2/default.nix
@@ -10,11 +10,6 @@
 , qt5
 , shiboken2
 }:
-
-# Only build when Python<=3.10
-# See https://bugreports.qt.io/browse/PYSIDE-1864
-# "There are no plans to support Python versions > 3.10 in the 5.15 branch."
-disabledIf (pythonAtLeast "3.11") (
 stdenv.mkDerivation rec {
   pname = "pyside2";
   version = "5.15.11";
@@ -80,4 +75,4 @@ stdenv.mkDerivation rec {
     homepage = "https://wiki.qt.io/Qt_for_Python";
     maintainers = with maintainers; [ gebner ];
   };
-})
+}