diff --git a/pkgs/applications/window-managers/openbox/default.nix b/pkgs/applications/window-managers/openbox/default.nix
index 487a8a5b387a..56a5f0e3e2ce 100644
--- a/pkgs/applications/window-managers/openbox/default.nix
+++ b/pkgs/applications/window-managers/openbox/default.nix
@@ -1,6 +1,6 @@
 { stdenv, fetchurl, pkgconfig
 , libxml2, libXinerama, libXcursor, libXau, libXrandr
-, imlib2, pango, libstartup_notification }:
+, imlib2, pango, libstartup_notification, makeWrapper}:
 
 stdenv.mkDerivation rec {
   name = "openbox-3.5.2";
@@ -9,6 +9,7 @@ stdenv.mkDerivation rec {
     pkgconfig libxml2
     libXinerama libXcursor libXau libXrandr
     imlib2 pango libstartup_notification
+    makeWrapper
   ];
 
   src = fetchurl {
@@ -16,6 +17,14 @@ stdenv.mkDerivation rec {
     sha256 = "0cxgb334zj6aszwiki9g10i56sm18i7w1kw52vdnwgzq27pv93qj";
   };
 
+  # Openbox needs XDG_DATA_DIRS set or it can't find its default theme
+  postInstall = ''
+    wrapProgram "$out/bin/openbox" --prefix XDG_DATA_DIRS : "$out/share"
+    wrapProgram "$out/bin/openbox-session" --prefix XDG_DATA_DIRS : "$out/share"
+    wrapProgram "$out/bin/openbox-gnome-session" --prefix XDG_DATA_DIRS : "$out/share"
+    wrapProgram "$out/bin/openbox-kde-session" --prefix XDG_DATA_DIRS : "$out/share"
+    '';
+
   meta = {
     description = "X window manager for non-desktop embedded systems";
     homepage = http://openbox.org/;