src/HOL/HOL.thy

   val hyp_subst_tacs = [Hypsubst.hyp_subst_tac]
 );
 
 structure Basic_Classical: BASIC_CLASSICAL = Classical; 
 open Basic_Classical;
-
-ML_Antiquote.value "claset"
-  (Scan.succeed "Classical.claset_of (ML_Context.the_local_context ())");
+*}
+
+setup {*
+  ML_Antiquote.value @{binding claset}
+    (Scan.succeed "Classical.claset_of (ML_Context.the_local_context ())")
 *}
 
 setup Classical.setup
 
 setup {*