src/Provers/clasimp.ML

   in
     PARALLEL_GOALS (ALLGOALS (Simplifier.asm_full_simp_tac ctxt)) THEN
     TRY (Classical.safe_tac ctxt) THEN
     REPEAT_DETERM (FIRSTGOAL main_tac) THEN
     TRY (Classical.safe_tac (addSss ctxt)) THEN
-    prune_params_tac
+    prune_params_tac ctxt
   end;
 
 fun auto_tac ctxt = mk_auto_tac ctxt 4 2;