diff -r 23d2cbac6dce -r 9429e7b5b827 src/HOL/Tools/Metis/metis_tactic.ML
--- a/src/HOL/Tools/Metis/metis_tactic.ML	Sun Feb 16 21:09:47 2014 +0100
+++ b/src/HOL/Tools/Metis/metis_tactic.ML	Sun Feb 16 21:33:28 2014 +0100
@@ -283,7 +283,7 @@
 
 fun set_opt _ x NONE = SOME x
   | set_opt get x (SOME x0) =
-    error ("Cannot specify both " ^ quote (get x0) ^ " and " ^ quote (get x) ^ ".")
+    error ("Cannot specify both " ^ quote (get x0) ^ " and " ^ quote (get x))
 
 fun consider_opt s =
   if member (op =) metis_lam_transs s then apsnd (set_opt I s) else apfst (set_opt hd [s])