diff --git a/ompi/datatype/dt_destroy.c b/ompi/datatype/dt_destroy.c
index 7910e29efa..1e02b7efc6 100644
--- a/ompi/datatype/dt_destroy.c
+++ b/ompi/datatype/dt_destroy.c
@@ -3,7 +3,7 @@
  * Copyright (c) 2004-2006 The Trustees of Indiana University and Indiana
  *                         University Research and Technology
  *                         Corporation.  All rights reserved.
- * Copyright (c) 2004-2006 The University of Tennessee and The University
+ * Copyright (c) 2004-2007 The University of Tennessee and The University
  *                         of Tennessee Research Foundation.  All rights
  *                         reserved.
  * Copyright (c) 2004-2006 High Performance Computing Center Stuttgart,
@@ -25,7 +25,7 @@ int32_t ompi_ddt_destroy( ompi_datatype_t** dt )
 {
     ompi_datatype_t* pData = *dt;
 
-    if( pData->flags & DT_FLAG_PREDEFINED )
+    if( (pData->flags & DT_FLAG_PREDEFINED) && (pData->super.obj_reference_count <= 1) )
         return OMPI_ERROR;
 
     OBJ_RELEASE( pData );
diff --git a/ompi/mpi/c/type_dup.c b/ompi/mpi/c/type_dup.c
index 864445b536..2087485607 100644
--- a/ompi/mpi/c/type_dup.c
+++ b/ompi/mpi/c/type_dup.c
@@ -2,7 +2,7 @@
  * Copyright (c) 2004-2005 The Trustees of Indiana University and Indiana
  *                         University Research and Technology
  *                         Corporation.  All rights reserved.
- * Copyright (c) 2004-2005 The University of Tennessee and The University
+ * Copyright (c) 2004-2007 The University of Tennessee and The University
  *                         of Tennessee Research Foundation.  All rights
  *                         reserved.
  * Copyright (c) 2004-2005 High Performance Computing Center Stuttgart, 
@@ -47,7 +47,15 @@ int MPI_Type_dup (MPI_Datatype type,
       }
    }
 
-   
+   /* Don't allow for UB and LB duplication. Instead return the same
+    * pointer and increase the reference count by one.
+    */
+   if( (MPI_UB == type) || (MPI_LB == type) ) {
+       OBJ_RETAIN( type );
+       *newtype = type;
+       return OMPI_SUCCESS;
+   }
+
    if( (rc = ompi_ddt_duplicate( type, newtype )) != MPI_SUCCESS ) {
       ompi_ddt_destroy( newtype );
       OMPI_ERRHANDLER_RETURN( MPI_ERR_INTERN, MPI_COMM_WORLD,