diff --git a/dhp-pace-core/src/main/java/eu/dnetlib/pace/model/SparkModel.scala b/dhp-pace-core/src/main/java/eu/dnetlib/pace/model/SparkModel.scala
index 3ba36aa22..aa997c6e9 100644
--- a/dhp-pace-core/src/main/java/eu/dnetlib/pace/model/SparkModel.scala
+++ b/dhp-pace-core/src/main/java/eu/dnetlib/pace/model/SparkModel.scala
@@ -78,10 +78,10 @@ case class SparkModel(conf: DedupConfig) {
               uv
 
             case Type.List | Type.JSON =>
-              Seq(MapDocumentUtil.truncateList(
+              MapDocumentUtil.truncateList(
                 MapDocumentUtil.getJPathList(fdef.getPath, documentContext, fdef.getType),
                 fdef.getSize
-              ))
+              ).asScala
 
             case Type.StringConcat =>
               val jpaths = CONCAT_REGEX.split(fdef.getPath)