diff --git a/public/biopet-extensions/src/main/scala/nl/lumc/sasc/biopet/extensions/Pysvtools.scala b/public/biopet-extensions/src/main/scala/nl/lumc/sasc/biopet/extensions/Pysvtools.scala
index d9ee8e68a5e9237341a3838718523741b9c90465..e7b87696ba1b3556113ad0a97a34321b8fef08a7 100644
--- a/public/biopet-extensions/src/main/scala/nl/lumc/sasc/biopet/extensions/Pysvtools.scala
+++ b/public/biopet-extensions/src/main/scala/nl/lumc/sasc/biopet/extensions/Pysvtools.scala
@@ -33,7 +33,7 @@ class Pysvtools(val root: Configurable) extends BiopetCommandLineFunction {
   @Argument(doc = "Set flanking amount")
   var flanking: Option[Int] = config("flanking")
 
-  var exclusionRegions: List[File] = config("exclusion_regions")
+  var exclusionRegions: List[File] = config("exclusion_regions", default = Nil)
   var translocationsOnly: Boolean = config("translocations_only", default = false)
 
   @Output(doc = "Unzipped file", required = true)