diff --git a/navalplanner-business/src/main/java/org/navalplanner/business/planner/entities/GenericDayAssignment.java b/navalplanner-business/src/main/java/org/navalplanner/business/planner/entities/GenericDayAssignment.java
index 7a7d0ccb6..b5c53580b 100644
--- a/navalplanner-business/src/main/java/org/navalplanner/business/planner/entities/GenericDayAssignment.java
+++ b/navalplanner-business/src/main/java/org/navalplanner/business/planner/entities/GenericDayAssignment.java
@@ -20,6 +20,7 @@
 
 package org.navalplanner.business.planner.entities;
 
+import java.util.Arrays;
 import java.util.Collection;
 import java.util.HashSet;
 import java.util.Set;
@@ -80,6 +81,7 @@ public class GenericDayAssignment extends DayAssignment {
 
     public void detach() {
         genericResourceAllocation = null;
+        getResource().removeAssignments(Arrays.asList(this));
     }
 
 }
diff --git a/navalplanner-business/src/main/java/org/navalplanner/business/planner/entities/SpecificDayAssignment.java b/navalplanner-business/src/main/java/org/navalplanner/business/planner/entities/SpecificDayAssignment.java
index 3a0ffa49a..e79bb4202 100644
--- a/navalplanner-business/src/main/java/org/navalplanner/business/planner/entities/SpecificDayAssignment.java
+++ b/navalplanner-business/src/main/java/org/navalplanner/business/planner/entities/SpecificDayAssignment.java
@@ -20,6 +20,7 @@
 
 package org.navalplanner.business.planner.entities;
 
+import java.util.Arrays;
 import java.util.Collection;
 import java.util.HashSet;
 import java.util.Set;
@@ -81,5 +82,6 @@ public class SpecificDayAssignment extends DayAssignment {
 
     void detach() {
         this.specificResourceAllocation = null;
+        getResource().removeAssignments(Arrays.asList(this));
     }
 }
diff --git a/navalplanner-business/src/main/java/org/navalplanner/business/resources/entities/Resource.java b/navalplanner-business/src/main/java/org/navalplanner/business/resources/entities/Resource.java
index eca6b10b7..8a74eb26b 100644
--- a/navalplanner-business/src/main/java/org/navalplanner/business/resources/entities/Resource.java
+++ b/navalplanner-business/src/main/java/org/navalplanner/business/resources/entities/Resource.java
@@ -596,6 +596,13 @@ public abstract class Resource extends BaseEntity{
         this.dayAssignments.addAll(assignments);
     }
 
+    public void removeAssignments(
+            Collection<? extends DayAssignment> assignments) {
+        Validate.noNullElements(assignments);
+        clearCachedData();
+        this.dayAssignments.removeAll(assignments);
+    }
+
     public List<DayAssignment> getAssignments() {
         return new ArrayList<DayAssignment>(dayAssignments);
     }