diff --git a/pkgs/development/python-modules/ndtypes/default.nix b/pkgs/development/python-modules/ndtypes/default.nix
index f3827206deb1..8bfe1347e6df 100644
--- a/pkgs/development/python-modules/ndtypes/default.nix
+++ b/pkgs/development/python-modules/ndtypes/default.nix
@@ -12,6 +12,8 @@ buildPythonPackage {
   disabled = isPy27;
   inherit (libndtypes) version src meta;
 
+  outputs = [ "out" "dev" ];
+
   propagatedBuildInputs = [ numpy ];
 
   postPatch = ''