diff --git a/navalplanner-business/src/main/java/org/navalplanner/business/advance/entities/AdvanceAssigment.java b/navalplanner-business/src/main/java/org/navalplanner/business/advance/entities/AdvanceAssigment.java
index d8b0d05d2..9b8b00712 100644
--- a/navalplanner-business/src/main/java/org/navalplanner/business/advance/entities/AdvanceAssigment.java
+++ b/navalplanner-business/src/main/java/org/navalplanner/business/advance/entities/AdvanceAssigment.java
@@ -1,6 +1,7 @@
 package org.navalplanner.business.advance.entities;
 
 import java.math.BigDecimal;
+import java.util.HashSet;
 import java.util.Set;
 
 import org.navalplanner.business.common.BaseEntity;
@@ -62,6 +63,6 @@ public class AdvanceAssigment extends BaseEntity {
     }
 
     public Set<AdvanceMeasurement> getAdvanceMeasurements() {
-        return this.advanceMeasurements;
+        return new HashSet<AdvanceMeasurement>(this.advanceMeasurements);
     }
 }
diff --git a/navalplanner-business/src/main/java/org/navalplanner/business/workreports/entities/WorkReportLine.java b/navalplanner-business/src/main/java/org/navalplanner/business/workreports/entities/WorkReportLine.java
index 6090228e3..76f485e61 100644
--- a/navalplanner-business/src/main/java/org/navalplanner/business/workreports/entities/WorkReportLine.java
+++ b/navalplanner-business/src/main/java/org/navalplanner/business/workreports/entities/WorkReportLine.java
@@ -69,7 +69,7 @@ public class WorkReportLine extends BaseEntity {
     }
 
     public Set<Criterion> getCriterions() {
-        return criterions;
+        return new HashSet<Criterion>(criterions);
     }
 
     public void setCriterions(Set<Criterion> criterions) {
diff --git a/navalplanner-business/src/main/java/org/navalplanner/business/workreports/entities/WorkReportType.java b/navalplanner-business/src/main/java/org/navalplanner/business/workreports/entities/WorkReportType.java
index 5aac7066b..cc9aa045b 100644
--- a/navalplanner-business/src/main/java/org/navalplanner/business/workreports/entities/WorkReportType.java
+++ b/navalplanner-business/src/main/java/org/navalplanner/business/workreports/entities/WorkReportType.java
@@ -1,5 +1,6 @@
 package org.navalplanner.business.workreports.entities;
 
+import java.util.HashSet;
 import java.util.Set;
 
 import org.navalplanner.business.common.BaseEntity;
@@ -33,7 +34,7 @@ public class WorkReportType extends BaseEntity {
     }
 
     public Set<CriterionType> getCriterionTypes() {
-        return criterionTypes;
+        return new HashSet<CriterionType>(criterionTypes);
     }
 
     public void setCriterionTypes(Set<CriterionType> criterionTypes) {