diff --git a/dhp-workflows/dhp-graph-mapper/src/main/java/eu/dnetlib/dhp/oa/graph/raw/MergeClaimsApplication.java b/dhp-workflows/dhp-graph-mapper/src/main/java/eu/dnetlib/dhp/oa/graph/raw/MergeClaimsApplication.java
index 635402a72..901252878 100644
--- a/dhp-workflows/dhp-graph-mapper/src/main/java/eu/dnetlib/dhp/oa/graph/raw/MergeClaimsApplication.java
+++ b/dhp-workflows/dhp-graph-mapper/src/main/java/eu/dnetlib/dhp/oa/graph/raw/MergeClaimsApplication.java
@@ -54,7 +54,7 @@ public class MergeClaimsApplication {
 		final GraphFormat format = Optional
 			.ofNullable(parser.get("format"))
 			.map(GraphFormat::valueOf)
-			.orElse(GraphFormat.JSON);
+			.orElse(GraphFormat.DEFAULT);
 		log.info("graphFormat: {}", format);
 
 		String graphTableClassName = parser.get("graphTableClassName");
diff --git a/dhp-workflows/dhp-workflows-common/src/main/java/eu/dnetlib/dhp/common/GraphFormat.java b/dhp-workflows/dhp-workflows-common/src/main/java/eu/dnetlib/dhp/common/GraphFormat.java
index 865f4a590..76a42fb5a 100644
--- a/dhp-workflows/dhp-workflows-common/src/main/java/eu/dnetlib/dhp/common/GraphFormat.java
+++ b/dhp-workflows/dhp-workflows-common/src/main/java/eu/dnetlib/dhp/common/GraphFormat.java
@@ -3,6 +3,8 @@ package eu.dnetlib.dhp.common;
 
 public enum GraphFormat {
 
-	JSON, HIVE
+	JSON, HIVE;
+
+	public static GraphFormat DEFAULT = JSON;
 
 }