diff --git a/default.nix b/default.nix
index d1b6140..569af15 100644
--- a/default.nix
+++ b/default.nix
@@ -12,7 +12,7 @@ let
 in
 
 self: super: rec {
-  python39 = pkgs.python39.override {
+  python39 = self.python39.override {
     packageOverrides = python-self: python-super: {
       strawberry_graphql = python-super.buildPythonPackage rec {
         pname = "strawberry-graphql";