diff --git a/libSM.spec b/libSM.spec
index de25b83..32e566d 100644
--- a/libSM.spec
+++ b/libSM.spec
@@ -13,6 +13,7 @@ BuildRequires: xorg-x11-proto-devel
 BuildRequires: xorg-x11-xtrans-devel >= 1.0.3-4
 BuildRequires: libICE-devel
 BuildRequires: libuuid-devel
+BuildRequires: xmlto
 
 %description
 The X.Org X11 SM (Session Management) runtime library.