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 60a76d8608c74aa51da3d5e858192c823f1427ce..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
@@ -38,6 +38,8 @@ class MergeOtuMaps(val root: Configurable) extends BiopetCommandLineFunction wit
 
   var failuresFp: Option[File] = None
 
+  override def defaultCoreMemory = 4.0
+
   override def beforeGraph(): Unit = {
     super.beforeGraph()
     require(input.nonEmpty)
diff --git a/public/biopet-extensions/src/main/scala/nl/lumc/sasc/biopet/extensions/qiime/PickClosedReferenceOtus.scala b/public/biopet-extensions/src/main/scala/nl/lumc/sasc/biopet/extensions/qiime/PickClosedReferenceOtus.scala
index 371752d378c22a22289cbf97addc55b75e1082c8..07fef8aef1ee831aa258555b2358660a396dea69 100644
--- a/public/biopet-extensions/src/main/scala/nl/lumc/sasc/biopet/extensions/qiime/PickClosedReferenceOtus.scala
+++ b/public/biopet-extensions/src/main/scala/nl/lumc/sasc/biopet/extensions/qiime/PickClosedReferenceOtus.scala
@@ -33,7 +33,7 @@ class PickClosedReferenceOtus(val root: Configurable) extends BiopetCommandLineF
   var outputDir: File = null
 
   override def defaultThreads = 3
-  override def defaultCoreMemory = 12.0
+  override def defaultCoreMemory = 16.0
   def versionCommand = executable + " --version"
   def versionRegex = """Version: (.*)""".r
 
diff --git a/public/biopet-extensions/src/main/scala/nl/lumc/sasc/biopet/extensions/qiime/SplitLibrariesFastq.scala b/public/biopet-extensions/src/main/scala/nl/lumc/sasc/biopet/extensions/qiime/SplitLibrariesFastq.scala
index cbf010ca75dc849435ef7b790f1892fd7af53ea6..d9295dee037381a4ff0504f0a7bf465cebd0f6b7 100644
--- a/public/biopet-extensions/src/main/scala/nl/lumc/sasc/biopet/extensions/qiime/SplitLibrariesFastq.scala
+++ b/public/biopet-extensions/src/main/scala/nl/lumc/sasc/biopet/extensions/qiime/SplitLibrariesFastq.scala
@@ -56,6 +56,8 @@ class SplitLibrariesFastq(val root: Configurable) extends BiopetCommandLineFunct
 
   def outputSeqs = new File(outputDir, "seqs.fna")
 
+  override def defaultCoreMemory = 4.0
+
   override def beforeGraph(): Unit = {
     super.beforeGraph()
     require(input.nonEmpty)