diff --git a/kudos-services/src/main/java/org/exoplatform/kudos/entity/KudosEntity.java b/kudos-services/src/main/java/org/exoplatform/kudos/entity/KudosEntity.java
index 2c8df8194..5e6770522 100644
--- a/kudos-services/src/main/java/org/exoplatform/kudos/entity/KudosEntity.java
+++ b/kudos-services/src/main/java/org/exoplatform/kudos/entity/KudosEntity.java
@@ -76,7 +76,7 @@ public class KudosEntity implements Serializable {
   @Column(name = "IS_RECEIVER_USER", nullable = false)
   public boolean            isReceiverUser;
 
-  @Column(name = "PARENT_ENTITY_ID", nullable = false)
+  @Column(name = "PARENT_ENTITY_ID", nullable = true)
   public Long               parentEntityId;
 
   @Column(name = "ENTITY_ID", nullable = false)
diff --git a/kudos-services/src/main/java/org/exoplatform/kudos/service/utils/Utils.java b/kudos-services/src/main/java/org/exoplatform/kudos/service/utils/Utils.java
index 8310fa3b2..6f7d6fa2d 100644
--- a/kudos-services/src/main/java/org/exoplatform/kudos/service/utils/Utils.java
+++ b/kudos-services/src/main/java/org/exoplatform/kudos/service/utils/Utils.java
@@ -202,6 +202,8 @@ public static KudosEntity toEntity(Kudos kudos) {
     kudosEntity.setActivityId(kudos.getActivityId());
     if (StringUtils.isNoneBlank(kudos.getParentEntityId())) {
       kudosEntity.setParentEntityId(Long.parseLong(kudos.getParentEntityId()));
+    } else {
+      kudosEntity.setParentEntityId(0l);
     }
     kudosEntity.setEntityType(KudosEntityType.valueOf(kudos.getEntityType()).ordinal());
     kudosEntity.setSenderId(Long.parseLong(kudos.getSenderIdentityId()));