diff --git a/pkgs/pkgs-lib/formats.nix b/pkgs/pkgs-lib/formats.nix
index 0836519c203d..25bdbdc8a08f 100644
--- a/pkgs/pkgs-lib/formats.nix
+++ b/pkgs/pkgs-lib/formats.nix
@@ -952,14 +952,13 @@ optionalAttrs allowAliases aliases
           pkgs.callPackage (
             {
               runCommand,
-              python3,
               libxml2Python,
+              python3Packages,
             }:
             runCommand name
               {
                 nativeBuildInputs = [
-                  python3
-                  python3.pkgs.xmltodict
+                  python3Packages.xmltodict
                   libxml2Python
                 ];
                 value = builtins.toJSON value;