diff -r 046fe7ddfc4b -r f65a7fa2da6c src/HOL/Word/WordShift.thy
--- a/src/HOL/Word/WordShift.thy	Fri Feb 15 16:09:10 2008 +0100
+++ b/src/HOL/Word/WordShift.thy	Fri Feb 15 16:09:12 2008 +0100
@@ -1202,7 +1202,7 @@
   apply (clarsimp simp add : test_bit_rcat word_size)
   apply (subst refl [THEN test_bit_rsplit])
     apply (simp_all add: word_size 
-      refl [THEN length_word_rsplit_size [simplified le_def, simplified]])
+      refl [THEN length_word_rsplit_size [simplified not_less [symmetric], simplified]])
    apply safe
    apply (erule xtr7, rule len_gt_0 [THEN dtle])+
   done