diff -r efa178abe023 -r 8ebffdaf2ce2 src/Pure/PIDE/batch_session.scala
--- a/src/Pure/PIDE/batch_session.scala	Mon Mar 07 15:21:50 2016 +0100
+++ b/src/Pure/PIDE/batch_session.scala	Mon Mar 07 18:20:22 2016 +0100
@@ -58,7 +58,7 @@
         case _ =>
       }
 
-    prover_session.start("Isabelle", "-q " + quote(parent_session))
+    prover_session.start("Isabelle", List("-q", parent_session))
 
     batch_session
   }