diff -r 11a4001b06c6 -r b47193851dc6 src/Pure/Isar/proof.ML
--- a/src/Pure/Isar/proof.ML	Fri May 09 22:04:50 2014 +0200
+++ b/src/Pure/Isar/proof.ML	Fri May 09 22:14:06 2014 +0200
@@ -1064,7 +1064,10 @@
     fun print_rule ctxt th =
       if ! testing then rule := SOME th
       else if int then
-        writeln (Markup.markup Markup.state (Proof_Display.string_of_rule ctxt "Successful" th))
+        Proof_Display.string_of_rule ctxt "Successful" th
+        |> Markup.markup Markup.text_fold
+        |> Markup.markup Markup.state
+        |> writeln
       else ();
     val test_proof =
       local_skip_proof true