diff --git a/public/biopet-extensions/src/main/scala/nl/lumc/sasc/biopet/extensions/picard/SortVcf.scala b/public/biopet-extensions/src/main/scala/nl/lumc/sasc/biopet/extensions/picard/SortVcf.scala
index b43e9f61b5c704bfed7fd7f62d8de8d1ba889e5f..36f31b399e84b916232e1498bee3a93420cc766e 100644
--- a/public/biopet-extensions/src/main/scala/nl/lumc/sasc/biopet/extensions/picard/SortVcf.scala
+++ b/public/biopet-extensions/src/main/scala/nl/lumc/sasc/biopet/extensions/picard/SortVcf.scala
@@ -31,7 +31,7 @@ class SortVcf(val root: Configurable) extends Picard {
   var output: File = _
 
   @Argument(doc = "Sequence dictionary to use", required = false)
-  var sequenceDictionary: String = config("sort_order", default = "coordinate")
+  var sequenceDictionary: File = _
 
   /** Returns command to execute */
   override def cmdLine = super.cmdLine +