diff --git a/pkgs/development/python-modules/django-pglocks/default.nix b/pkgs/development/python-modules/django-pglocks/default.nix
index da1dfe21df2..5963b24c830 100644
--- a/pkgs/development/python-modules/django-pglocks/default.nix
+++ b/pkgs/development/python-modules/django-pglocks/default.nix
@@ -1,4 +1,4 @@
-{ lib, buildPythonPackage, fetchPypi, django }:
+{ lib, buildPythonPackage, fetchPypi, django, six }:
 
 buildPythonPackage rec {
   pname = "django-pglocks";
@@ -16,7 +16,7 @@ buildPythonPackage rec {
   };
 
   buildInputs = [ django ];
-  propagatedBuildInputs = [ django ];
+  propagatedBuildInputs = [ django six ];
 
   # tests need a postgres database
   doCheck = false;