diff --git a/default.nix b/default.nix
index 7c56d29..0c6f148 100644
--- a/default.nix
+++ b/default.nix
@@ -9,7 +9,7 @@ self: super: rec {
         pname = "graphql-core";
           version = "3.2.0";
           format = "setuptools";
-          src = fetchPypi {
+          src = python-super.fetchPypi {
             inherit pname version;
             sha256 = "sha256-huKgvgCL/eGe94OI3opyWh2UKpGQykMcJKYIN5c4A84=";
           };