diff --git a/pkgs/development/interpreters/python/cpython/3.9/darwin-tcl-tk.patch b/pkgs/development/interpreters/python/cpython/3.9/darwin-tcl-tk.patch
new file mode 100644
index 000000000000..a9b0c0677c5e
--- /dev/null
+++ b/pkgs/development/interpreters/python/cpython/3.9/darwin-tcl-tk.patch
@@ -0,0 +1,15 @@
+diff --git a/setup.py b/setup.py
+index 04eb6b2..2e1160d 100644
+--- a/setup.py
++++ b/setup.py
+@@ -1981,8 +1981,8 @@ class PyBuildExt(build_ext):
+         # Rather than complicate the code below, detecting and building
+         # AquaTk is a separate method. Only one Tkinter will be built on
+         # Darwin - either AquaTk, if it is found, or X11 based Tk.
+-        if (MACOS and self.detect_tkinter_darwin()):
+-            return True
++        # if (MACOS and self.detect_tkinter_darwin()):
++        #     return True
+ 
+         # Assume we haven't found any of the libraries or include files
+         # The versions with dots are used on Unix, and the versions without
diff --git a/pkgs/development/interpreters/python/cpython/default.nix b/pkgs/development/interpreters/python/cpython/default.nix
index d59d3cb44708..76a66a648d84 100644
--- a/pkgs/development/interpreters/python/cpython/default.nix
+++ b/pkgs/development/interpreters/python/cpython/default.nix
@@ -235,6 +235,9 @@ in with passthru; stdenv.mkDerivation {
       else
         ./3.5/profile-task.patch
     )
+  ] ++ optionals (pythonAtLeast "3.9" && stdenv.isDarwin) [
+    # Stop checking for TCL/TK in global macOS locations
+    ./3.9/darwin-tcl-tk.patch
   ] ++ optionals (isPy3k && hasDistutilsCxxPatch) [
     # Fix for http://bugs.python.org/issue1222585
     # Upstream distutils is calling C compiler to compile C++ code, which
@@ -335,6 +338,8 @@ in with passthru; stdenv.mkDerivation {
   '' + optionalString stdenv.isDarwin ''
     export NIX_CFLAGS_COMPILE="$NIX_CFLAGS_COMPILE -msse2"
     export MACOSX_DEPLOYMENT_TARGET=10.6
+    # Override the auto-detection in setup.py, which assumes a universal build
+    export PYTHON_DECIMAL_WITH_MACHINE=${if stdenv.isAarch64 then "uint128" else "x64"}
   '' + optionalString (isPy3k && pythonOlder "3.7") ''
     # Determinism: The interpreter is patched to write null timestamps when compiling Python files
     #   so Python doesn't try to update the bytecode when seeing frozen timestamps in Nix's store.