--- a/src/HOL/IMPP/Natural.thy Sun Nov 09 20:49:28 2014 +0100
+++ b/src/HOL/IMPP/Natural.thy Mon Nov 10 21:49:48 2014 +0100
@@ -139,7 +139,8 @@
lemma evalc_evaln: "<c,s> -c-> t ==> ? n. <c,s> -n-> t"
apply (erule evalc.induct)
apply (tactic {* ALLGOALS (REPEAT o etac exE) *})
-apply (tactic {* TRYALL (EVERY' [dtac @{thm evaln_max2}, assume_tac, REPEAT o eresolve_tac [exE, conjE]]) *})
+apply (tactic {* TRYALL (EVERY' [dtac @{thm evaln_max2}, assume_tac @{context},
+ REPEAT o eresolve_tac [exE, conjE]]) *})
apply (tactic {* ALLGOALS (rtac exI THEN' resolve_tac @{thms evaln.intros} THEN_ALL_NEW atac) *})
done