src/HOL/Tools/SMT/smt_systems.ML

     "--disable-banner",
     "--max-time=" ^ string_of_int (Real.ceil (Config.get ctxt SMT_Config.timeout))]),
   smt_options = [(":produce-proofs", "true")],
   default_max_relevant = 200 (* FUDGE *),
   outcome = on_first_non_unsupported_line (outcome_of "unsat" "sat"
-    "warning : proof_done: status is still open"),
+    "(error \"status is not unsat.\")"),
   parse_proof = SOME (K VeriT_Proof_Parse.parse_proof),
   replay = NONE }
 
 (* Z3 *)