diff --git a/pkgs/development/python-modules/generic/default.nix b/pkgs/development/python-modules/generic/default.nix
index aa24bc78a65..6583373f322 100644
--- a/pkgs/development/python-modules/generic/default.nix
+++ b/pkgs/development/python-modules/generic/default.nix
@@ -3,12 +3,14 @@
    (http://pypi.python.org/pypi/setuptools/), which represents a large
    number of Python packages nowadays.  */
 
-{ python, setuptools, wrapPython, lib, offlineDistutils }:
+{ python, setuptools, wrapPython, lib, offlineDistutils, setuptoolsSite }:
 
 { name, namePrefix ? "python-"
 
 , buildInputs ? []
 
+, propagatedBuildInputs ? []
+
 , # List of packages that should be added to the PYTHONPATH
   # environment variable in programs built by this function.  Packages
   # in the standard `propagatedBuildInputs' variable are also added.
@@ -47,6 +49,9 @@ python.stdenv.mkDerivation (attrs // {
 
   buildInputs = [ python wrapPython setuptools ] ++ buildInputs ++ pythonPath;
 
+  # setuptoolsSite is responsible for loading pth files
+  propagatedBuildInputs = propagatedBuildInputs ++ [ setuptoolsSite ];
+
   buildInputStrings = map toString buildInputs;
 
   pythonPath = [ setuptools] ++ pythonPath;