diff --git a/pkgs/tools/X11/obconf/default.nix b/pkgs/tools/X11/obconf/default.nix
index cb3749efb44..49bab143fc2 100644
--- a/pkgs/tools/X11/obconf/default.nix
+++ b/pkgs/tools/X11/obconf/default.nix
@@ -1,5 +1,5 @@
 { stdenv, fetchurl, pkgconfig, gtk2, libglade, openbox,
-  imlib2, libstartup_notification, makeWrapper }:
+  imlib2, libstartup_notification, makeWrapper, libSM }:
 
 stdenv.mkDerivation rec {
   name = "obconf-${version}";
@@ -11,7 +11,8 @@ stdenv.mkDerivation rec {
   };
 
   buildInputs = [
-    pkgconfig gtk2 libglade openbox imlib2 libstartup_notification makeWrapper
+    pkgconfig gtk2 libglade libSM openbox imlib2 libstartup_notification
+    makeWrapper
   ];
 
   postInstall = ''