start our own Xvfb process
diff --git a/releng.control/commonVariations.shsource b/releng.control/commonVariations.shsource
index 2239098..f860371 100644
--- a/releng.control/commonVariations.shsource
+++ b/releng.control/commonVariations.shsource
@@ -26,7 +26,7 @@
 export RELENG_CONTROL=${BUILD_HOME}/releng.control
 
 # this variable must batch the screen number that Xvfb is using
-export DISPLAYNUMBER
+export DISPLAYNUMBER=1001
 export DISPLAY=127.0.0.1:$DISPLAYNUMBER.0
 
 # these should be full, abosolute path to the respective home directories