diff --git a/automation/scripts/build b/automation/scripts/build
index 7a81d229de..359ee18444 100755
--- a/automation/scripts/build
+++ b/automation/scripts/build
@@ -27,7 +27,8 @@ else
     # Start off with arch's defconfig
     make -C xen defconfig
 
-    echo "CONFIG_DEBUG=${debug}" >> xen/.config
+    debug="${debug:-n}"
+    xen/scripts/config --file xen/.config -${debug} DEBUG
 
     if [[ -n "${EXTRA_XEN_CONFIG}" ]]; then
         echo "${EXTRA_XEN_CONFIG}" >> xen/.config