diff -r 7b860fa1140f -r 6b998ce1b8cb src/Pure/Admin/build_vampire.scala
--- a/src/Pure/Admin/build_vampire.scala	Wed Sep 15 16:11:53 2021 +0200
+++ b/src/Pure/Admin/build_vampire.scala	Wed Sep 15 16:13:25 2021 +0200
@@ -95,8 +95,6 @@
 
 ISABELLE_VAMPIRE="$VAMPIRE_HOME/vampire"
 ISABELLE_VAMPIRE_POLYMORPHIC="$VAMPIRE_HOME/vampire_polymorphic"
-
-VAMPIRE_EXTRA_OPTIONS=""
 """)