
diff -r 3610e0a7693c -r 36489d77c484 src/HOL/Rat.thy
--- a/src/HOL/Rat.thy	Fri Apr 04 16:43:47 2014 +0200
+++ b/src/HOL/Rat.thy	Thu Apr 03 23:51:52 2014 +0100
@@ -665,7 +665,7 @@
   by transfer (simp add: add_frac_eq)
 
 lemma of_rat_minus: "of_rat (- a) = - of_rat a"
-  by transfer simp
+  by transfer (simp add: divide_minus_left)
 
 lemma of_rat_neg_one [simp]:
   "of_rat (- 1) = - 1"




