diff -r 851ae0e7b09c -r 37074e22e8be src/Pure/Concurrent/standard_thread.ML
--- a/src/Pure/Concurrent/standard_thread.ML	Tue Dec 13 11:51:42 2016 +0100
+++ b/src/Pure/Concurrent/standard_thread.ML	Tue Dec 13 23:29:54 2016 +0100
@@ -50,7 +50,8 @@
 
 fun attributes ({stack_limit, interrupts, ...}: params) =
   Thread.MaximumMLStack stack_limit ::
-  (if interrupts then Thread_Attributes.public_interrupts else Thread_Attributes.no_interrupts);
+  Thread_Attributes.convert_attributes
+    (if interrupts then Thread_Attributes.public_interrupts else Thread_Attributes.no_interrupts);
 
 fun fork (params: params) body =
   Thread.fork (fn () =>