diff --git a/public/biopet-extensions/src/main/scala/nl/lumc/sasc/biopet/extensions/qiime/MergeOtuMaps.scala b/public/biopet-extensions/src/main/scala/nl/lumc/sasc/biopet/extensions/qiime/MergeOtuMaps.scala
index ce070ccff0b2dd7973e376344f61095ec6815e8e..db9ed0f7e3c4875afcf94babe19cd686783107de 100644
--- a/public/biopet-extensions/src/main/scala/nl/lumc/sasc/biopet/extensions/qiime/MergeOtuMaps.scala
+++ b/public/biopet-extensions/src/main/scala/nl/lumc/sasc/biopet/extensions/qiime/MergeOtuMaps.scala
@@ -38,7 +38,7 @@ class MergeOtuMaps(val root: Configurable) extends BiopetCommandLineFunction wit
 
   var failuresFp: Option[File] = None
 
-  override def defaultCoreMemory = 8.0
+  override def defaultCoreMemory = 4.0
 
   override def beforeGraph(): Unit = {
     super.beforeGraph()
diff --git a/public/biopet-extensions/src/main/scala/nl/lumc/sasc/biopet/extensions/qiime/MergeOtuTables.scala b/public/biopet-extensions/src/main/scala/nl/lumc/sasc/biopet/extensions/qiime/MergeOtuTables.scala
index 86b481761137bc598992e26b3f41a4cfcef4fc97..1f5d5d1e944546568ae2f89ca3dae71567e0871b 100644
--- a/public/biopet-extensions/src/main/scala/nl/lumc/sasc/biopet/extensions/qiime/MergeOtuTables.scala
+++ b/public/biopet-extensions/src/main/scala/nl/lumc/sasc/biopet/extensions/qiime/MergeOtuTables.scala
@@ -36,6 +36,8 @@ class MergeOtuTables(val root: Configurable) extends BiopetCommandLineFunction w
   @Output(required = true)
   var outputFile: File = _
 
+  override def defaultCoreMemory = 4.0
+
   override def beforeGraph(): Unit = {
     super.beforeGraph()
     require(input.nonEmpty)