diff --git a/SysBuild/BuildCluster/XTools.dmk b/SysBuild/BuildCluster/XTools.dmk
index dd0176a..264cc3f 100644
--- a/SysBuild/BuildCluster/XTools.dmk
+++ b/SysBuild/BuildCluster/XTools.dmk
@@ -56,3 +56,4 @@
 0	guibased/gtkglarea
 0	guibased/xscreensaver
 0	network/firefox
+0	network/thunderbird
diff --git a/SysBuild/DistCluster.dmk b/SysBuild/DistCluster.dmk
index 70b7e56..193a617 100644
--- a/SysBuild/DistCluster.dmk
+++ b/SysBuild/DistCluster.dmk
@@ -48,4 +48,4 @@
 256	BuildCluster/XServ.dmk
 256	BuildCluster/Tools.dmk
 256	BuildCluster/XBaseLibs.dmk
-#256	BuildCluster/XTools.dmk
+256	BuildCluster/XTools.dmk