diff --git a/Microsoft.SystemForCrossDomainIdentityManagement/Protocol/ProtocolExtensions.cs b/Microsoft.SystemForCrossDomainIdentityManagement/Protocol/ProtocolExtensions.cs
index f448e095..262502ac 100644
--- a/Microsoft.SystemForCrossDomainIdentityManagement/Protocol/ProtocolExtensions.cs
+++ b/Microsoft.SystemForCrossDomainIdentityManagement/Protocol/ProtocolExtensions.cs
@@ -201,6 +201,13 @@ private static void Apply(this Core2Group group, PatchOperation2 operation)
                                 break;
                         }
                     }
+                    break;
+                case AttributeNames.ExternalIdentifier:
+
+                    value = operation.Value.SingleOrDefault();
+
+                    group.ExternalIdentifier= value?.Value;
+
                     break;
             }
         }