diff --git a/navalplanner-business/src/main/java/org/navalplanner/business/planner/limiting/entities/LimitingResourceQueueElement.java b/navalplanner-business/src/main/java/org/navalplanner/business/planner/limiting/entities/LimitingResourceQueueElement.java
index 68890e77b..5b5dd05f3 100644
--- a/navalplanner-business/src/main/java/org/navalplanner/business/planner/limiting/entities/LimitingResourceQueueElement.java
+++ b/navalplanner-business/src/main/java/org/navalplanner/business/planner/limiting/entities/LimitingResourceQueueElement.java
@@ -172,9 +172,9 @@ public class LimitingResourceQueueElement extends BaseEntity {
 
     public void add(LimitingResourceQueueDependency d) {
         Validate.notNull(d);
-        if (d.getHasAsOrigin().getId().equals(this.getId())) {
+        if (sameInDB(d.getHasAsOrigin())) {
             dependenciesAsOrigin.add(d);
-        } else if (d.getHasAsDestiny().getId().equals(this.getId())) {
+        } else if (sameInDB(d.getHasAsDestiny())) {
             dependenciesAsDestiny.add(d);
         } else {
             throw new IllegalArgumentException(
@@ -184,6 +184,11 @@ public class LimitingResourceQueueElement extends BaseEntity {
         }
     }
 
+    private boolean sameInDB(LimitingResourceQueueElement other) {
+        return this == other || other.getId() != null && this.getId() != null
+                && other.getId().equals(this.getId());
+    }
+
     public void remove(LimitingResourceQueueDependency d) {
         if (dependenciesAsOrigin.contains(d))
             dependenciesAsOrigin.remove(d);