diff --git a/navalplanner-business/src/main/java/org/navalplanner/business/orders/daos/HoursGroupDAO.java b/navalplanner-business/src/main/java/org/navalplanner/business/orders/daos/HoursGroupDAO.java
index fa371652f..a9e60deb7 100644
--- a/navalplanner-business/src/main/java/org/navalplanner/business/orders/daos/HoursGroupDAO.java
+++ b/navalplanner-business/src/main/java/org/navalplanner/business/orders/daos/HoursGroupDAO.java
@@ -20,6 +20,7 @@
 
 package org.navalplanner.business.orders.daos;
 
+import org.apache.commons.lang.Validate;
 import org.hibernate.Criteria;
 import org.hibernate.criterion.Restrictions;
 import org.navalplanner.business.common.daos.GenericDAOHibernate;
@@ -65,9 +66,8 @@ public class HoursGroupDAO extends GenericDAOHibernate<HoursGroup, Long>
 
     private HoursGroup findUniqueByCode(HoursGroup hoursGroup)
             throws InstanceNotFoundException {
-        if ((hoursGroup == null) || (hoursGroup.getCode() == null)) {
-            return null;
-        }
+        Validate.notNull(hoursGroup);
+        Validate.notNull(hoursGroup.getCode());
 
         Criteria c = getSession().createCriteria(HoursGroup.class);
         c.add(Restrictions.eq("code", hoursGroup.getCode()));
diff --git a/navalplanner-business/src/main/java/org/navalplanner/business/orders/entities/HoursGroup.java b/navalplanner-business/src/main/java/org/navalplanner/business/orders/entities/HoursGroup.java
index 5258c936a..7779a7704 100644
--- a/navalplanner-business/src/main/java/org/navalplanner/business/orders/entities/HoursGroup.java
+++ b/navalplanner-business/src/main/java/org/navalplanner/business/orders/entities/HoursGroup.java
@@ -26,6 +26,8 @@ import java.util.Collections;
 import java.util.HashSet;
 import java.util.Set;
 
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
 import org.hibernate.validator.AssertTrue;
 import org.hibernate.validator.NotEmpty;
 import org.hibernate.validator.NotNull;
@@ -43,6 +45,8 @@ import org.navalplanner.business.resources.entities.ResourceEnum;
 public class HoursGroup extends BaseEntity implements Cloneable,
         ICriterionRequirable {
 
+    private static final Log LOG = LogFactory.getLog(HoursGroup.class);
+
     public static HoursGroup create(OrderLine parentOrderLine) {
         HoursGroup result = new HoursGroup(parentOrderLine);
         result.setNewObject(true);
@@ -281,8 +285,12 @@ public class HoursGroup extends BaseEntity implements Cloneable,
 
     @AssertTrue(message = "code is already being used")
     public boolean checkConstraintUniqueCode() {
+        if (code == null) {
+            LOG.warn("Hours group code is null. "
+                    + "Not checking unique code since it would fail");
+            return true;
+        }
         IHoursGroupDAO hoursGroupDAO = Registry.getHoursGroupDAO();
-
         if (isNewObject()) {
             return !hoursGroupDAO.existsByCodeAnotherTransaction(this);
         } else {