diff --git a/pkgs/development/python-modules/pydot_ng/default.nix b/pkgs/development/python-modules/pydot_ng/default.nix
new file mode 100644
index 000000000000..a96c03bed4f1
--- /dev/null
+++ b/pkgs/development/python-modules/pydot_ng/default.nix
@@ -0,0 +1,34 @@
+{ stdenv
+, buildPythonPackage
+, fetchPypi
+, pyparsing
+, pytest
+, unittest2
+, pkgs
+}:
+
+buildPythonPackage rec {
+  pname = "pydot_ng";
+  version = "1.0.0";
+
+  src = fetchPypi {
+    inherit pname version;
+    sha256 = "0h8k8wlzvnb40v4js7afgfyhp3wasmb1kg4gr6z7ck63iv8fq864";
+  };
+
+  buildInputs = [ pytest unittest2 ];
+  propagatedBuildInputs = [ pkgs.graphviz pyparsing ];
+
+  checkPhase = ''
+    mkdir test/my_tests
+    py.test test
+  '';
+
+  meta = with stdenv.lib; {
+    homepage = "https://pypi.python.org/pypi/pydot-ng";
+    description = "Python 3-compatible update of pydot, a Python interface to Graphviz's Dot";
+    license = licenses.mit;
+    maintainers = [ maintainers.bcdarwin ];
+  };
+
+}
diff --git a/pkgs/top-level/python-packages.nix b/pkgs/top-level/python-packages.nix
index c11a884c3d91..4d8deec64bbb 100644
--- a/pkgs/top-level/python-packages.nix
+++ b/pkgs/top-level/python-packages.nix
@@ -3299,29 +3299,7 @@ in {
 
   pydot = callPackage ../development/python-modules/pydot { };
 
-  pydot_ng = buildPythonPackage rec {
-    name = "pydot_ng-1.0.0";
-
-    src = pkgs.fetchurl {
-      url = "mirror://pypi/p/pydot-ng/${name}.tar.gz";
-      sha256 = "0h8k8wlzvnb40v4js7afgfyhp3wasmb1kg4gr6z7ck63iv8fq864";
-    };
-
-    buildInputs = [ self.pytest self.unittest2 ];
-    propagatedBuildInputs = [ pkgs.graphviz self.pyparsing ];
-
-    checkPhase = ''
-      mkdir test/my_tests
-      py.test test
-    '';
-
-    meta = {
-      homepage = "https://pypi.python.org/pypi/pydot-ng";
-      description = "Python 3-compatible update of pydot, a Python interface to Graphviz's Dot";
-      license = licenses.mit;
-      maintainers = [ maintainers.bcdarwin ];
-    };
-  };
+  pydot_ng = callPackage ../development/python-modules/pydot_ng { };
 
   pyelftools = buildPythonPackage rec {
     pname = "pyelftools";