diff --git a/pkgs/all-packages.nix b/pkgs/all-packages.nix
index bd388c6..1b58c85 100644
--- a/pkgs/all-packages.nix
+++ b/pkgs/all-packages.nix
@@ -31,7 +31,6 @@ self: super: pkgs: with pkgs; {
   openfoam = callPackage ./openfoam.nix { };
 
   openslide = callPackage ./openslide { };
-  openslide-python = callPackage ./openslide/python.nix { pythonPackages = python27Packages; };
 
   ovito = libsForQt5.callPackage ./ovito.nix { stdenv = overrideCC stdenv gcc6; };
 
diff --git a/pkgs/openslide/python.nix b/pkgs/openslide/python.nix
index 415ce48..12fea5c 100644
--- a/pkgs/openslide/python.nix
+++ b/pkgs/openslide/python.nix
@@ -1,7 +1,8 @@
-{ lib, fetchFromGitHub
-, pythonPackages, openslide }:
+{ lib, fetchFromGitHub, buildPythonPackage
+, openslide
+, pillow }:
 
-pythonPackages.buildPythonPackage rec {
+buildPythonPackage rec {
   version = "1.1.1";
   name = "openslide-python-${version}";
 
@@ -23,7 +24,7 @@ pythonPackages.buildPythonPackage rec {
   ];
 
   propagatedBuildInputs = [
-    pythonPackages.pillow
+    pillow
   ];
 
   meta = with lib; {
diff --git a/pkgs/python-packages.nix b/pkgs/python-packages.nix
index ad9000e..3af8f7b 100644
--- a/pkgs/python-packages.nix
+++ b/pkgs/python-packages.nix
@@ -1,3 +1,4 @@
 pkgs: self: super: with self; {
 
+  openslide = callPackage ./openslide/python.nix { openslide = pkgs.openslide; };
 }