diff --git a/biopet-tools/src/main/scala/nl/lumc/sasc/biopet/tools/bamstats/BamStats.scala b/biopet-tools/src/main/scala/nl/lumc/sasc/biopet/tools/bamstats/BamStats.scala
index 5143c9e0c80aa0c797d0240963040b88d5f4ccff..db9164bb5734a6e195fed27ba6695f71336efb32 100644
--- a/biopet-tools/src/main/scala/nl/lumc/sasc/biopet/tools/bamstats/BamStats.scala
+++ b/biopet-tools/src/main/scala/nl/lumc/sasc/biopet/tools/bamstats/BamStats.scala
@@ -155,7 +155,7 @@ object BamStats extends ToolCommand {
     * @return Output stats
     */
   def processThread(scatters: List[BedRecord], bamFile: File): Stats = {
-    var totalStats = Stats()
+    val totalStats = Stats()
     val sortedScatters = scatters.sortBy(_.start)
     val samReader = SamReaderFactory.makeDefault().open(bamFile)
     val threadChr = sortedScatters.head.chr
@@ -206,7 +206,7 @@ object BamStats extends ToolCommand {
     * @return Output stats
     */
   def processUnmappedReads(bamFile: File): Stats = {
-    var stats = Stats()
+    val stats = Stats()
     val samReader = SamReaderFactory.makeDefault().open(bamFile)
     var size = samReader.queryUnmapped().size
     stats.totalReads += size