diff --git a/lib/resource.txt b/lib/resource.txt
index 8f00efb..6a3690d 100755
--- a/lib/resource.txt
+++ b/lib/resource.txt
@@ -60,6 +60,7 @@
 # The caller must set this to the string "true" in order to delete images. The
 # code is picky.
 ${DELETE_OLD_PNOR_IMAGES}   false
+${DELETE_OLD_GUARD_FILE}    false
 
 # Caller can specify a value for LAST_KNOWN_GOOD_VERSION to indicate that if
 # the machine already has that version on it, the update should be skipped.