diff -r 4bee6d8c1500 -r 26bf09b95dda src/HOL/Word/Word.thy
--- a/src/HOL/Word/Word.thy	Sun Nov 09 20:49:28 2014 +0100
+++ b/src/HOL/Word/Word.thy	Mon Nov 10 21:49:48 2014 +0100
@@ -1565,8 +1565,8 @@
       ALLGOALS  (fn n => REPEAT (resolve_tac [allI, impI] n) THEN      
                          REPEAT (etac conjE n) THEN
                          REPEAT (dtac @{thm word_of_int_inverse} n 
-                                 THEN atac n 
-                                 THEN atac n)),
+                                 THEN assume_tac ctxt n 
+                                 THEN assume_tac ctxt n)),
       TRYALL arith_tac' ]
   end