diff --git a/dhp-workflows/dhp-patch/src/main/java/eu/dnetlib/dhp/patchrefereed/SparkPatchRefereed.java b/dhp-workflows/dhp-patch/src/main/java/eu/dnetlib/dhp/patchrefereed/SparkPatchRefereed.java
index c566fc638..c0904ba5d 100644
--- a/dhp-workflows/dhp-patch/src/main/java/eu/dnetlib/dhp/patchrefereed/SparkPatchRefereed.java
+++ b/dhp-workflows/dhp-patch/src/main/java/eu/dnetlib/dhp/patchrefereed/SparkPatchRefereed.java
@@ -140,21 +140,19 @@ public class SparkPatchRefereed implements Serializable {
 		// ri.getHostedby().equals(i.getHostedby()) &&
 		// ri.getInstancetype().equals(i.getInstancetype()) &&
 			equals(ri.getUrl(), i.getUrl())) {
-			Optional<Qualifier> oRefereed = Optional.ofNullable(i.getRefereed());
-			if (!oRefereed.isPresent()) {
-				if (ri.getRefereed().getClassid().equals("")) {
-					i.setRefereed(Constants.DEFAULT_REFEREED);
-				} else {
-					i.setRefereed(ri.getRefereed());
-				}
-			}
+			// Optional<Qualifier> oRefereed = Optional.ofNullable(i.getRefereed());
+			// if (!oRefereed.isPresent()) {
+			// if (!(ri.getRefereed().getClassid().equals("") ||
+			// ri.getRefereed().getClassid().equals(Constants.DEFAULT_REFEREED.getClassid()))) {
+			i.setRefereed(ri.getRefereed());
 			return true;
+			// }
 		}
 		return false;
 	}
 
 	// TODO verify the reason of the NullPointerException fired at line 167
-	private static boolean equals(List<String> url, List<String> url1) {
+	public static boolean equals(List<String> url, List<String> url1) {
 		try {
 			if (url == null && url1 == null) {
 				return true;
diff --git a/dhp-workflows/dhp-patch/src/main/java/eu/dnetlib/dhp/patchrefereed/SparkPrepareResultInstanceList.java b/dhp-workflows/dhp-patch/src/main/java/eu/dnetlib/dhp/patchrefereed/SparkPrepareResultInstanceList.java
index 7a8a07923..a9c9888b2 100644
--- a/dhp-workflows/dhp-patch/src/main/java/eu/dnetlib/dhp/patchrefereed/SparkPrepareResultInstanceList.java
+++ b/dhp-workflows/dhp-patch/src/main/java/eu/dnetlib/dhp/patchrefereed/SparkPrepareResultInstanceList.java
@@ -97,10 +97,13 @@ public class SparkPrepareResultInstanceList implements Serializable {
 						.map(instance -> {
 							Optional<Qualifier> oRefereed = Optional.ofNullable(instance.getRefereed());
 							if (oRefereed.isPresent()) {
-								return instance;
-							} else {
-								return null;
+								if (!(oRefereed.get().getClassid().equals(Constants.DEFAULT_REFEREED.getClassid()) ||
+									oRefereed.get().getClassid().equals("UNKNOWN") ||
+									oRefereed.get().getClassid().equals(""))) {
+									return instance;
+								}
 							}
+							return null;
 						})
 						.filter(Objects::nonNull)
 						.collect(Collectors.toList()))