diff --git a/public/bam2wig/src/main/scala/nl/lumc/sasc/biopet/pipelines/bamtobigwig/Bam2Wig.scala b/public/bam2wig/src/main/scala/nl/lumc/sasc/biopet/pipelines/bamtobigwig/Bam2Wig.scala
index 4579851bd7501f35d11688681a19339fbbc30b35..e76acd863a3eed3ebdcb1a4b1b5654fe71d623b9 100644
--- a/public/bam2wig/src/main/scala/nl/lumc/sasc/biopet/pipelines/bamtobigwig/Bam2Wig.scala
+++ b/public/bam2wig/src/main/scala/nl/lumc/sasc/biopet/pipelines/bamtobigwig/Bam2Wig.scala
@@ -16,7 +16,7 @@ class Bam2Wig(val root: Configurable) extends QScript with BiopetQScript {
   def this() = this(null)
 
   @Input(doc = "Input bam file", required = true)
-  var bamFile: File = _
+  var bamFile: File = null
 
   def init(): Unit = {
   }