diff --git a/pkgs/desktops/gnome-3/core/gnome-session/default.nix b/pkgs/desktops/gnome-3/core/gnome-session/default.nix
index 57bcd826038d..973613b3319e 100644
--- a/pkgs/desktops/gnome-3/core/gnome-session/default.nix
+++ b/pkgs/desktops/gnome-3/core/gnome-session/default.nix
@@ -1,5 +1,5 @@
 { fetchurl, stdenv, substituteAll, meson, ninja, pkgconfig, gnome3, glib, gtk, gsettings-desktop-schemas
-, gnome-desktop, dbus, json-glib, libICE, xmlto, docbook_xsl, docbook_xml_dtd_412
+, gnome-desktop, dbus, json-glib, libICE, xmlto, docbook_xsl, docbook_xml_dtd_412, python3
 , libxslt, gettext, makeWrapper, systemd, xorg, epoxy }:
 
 stdenv.mkDerivation rec {
@@ -23,7 +23,7 @@ stdenv.mkDerivation rec {
 
   nativeBuildInputs = [
     meson ninja pkgconfig gettext makeWrapper
-    xmlto libxslt docbook_xsl docbook_xml_dtd_412
+    xmlto libxslt docbook_xsl docbook_xml_dtd_412 python3
     dbus # for DTD
   ];