diff --git a/ompi/mpi/c/comm_f2c.c b/ompi/mpi/c/comm_f2c.c
index f3e2dc6526..7e91b4881a 100644
--- a/ompi/mpi/c/comm_f2c.c
+++ b/ompi/mpi/c/comm_f2c.c
@@ -9,6 +9,7 @@
  *                         University of Stuttgart.  All rights reserved.
  * Copyright (c) 2004-2005 The Regents of the University of California.
  *                         All rights reserved.
+ * Copyright (c) 2006      Cisco Systems, Inc.  All rights reserved.
  * $COPYRIGHT$
  * 
  * Additional copyrights may follow
@@ -41,11 +42,12 @@ MPI_Comm MPI_Comm_f2c(MPI_Fint comm)
     }
 
     /* Per MPI-2:4.12.4, do not invoke an error handler if we get an
-       invalid fortran handle */
+       invalid fortran handle.  If we get an invalid fortran handle,
+       return an invalid C handle. */
 
     if ( 0 > o_index ||
          o_index >= ompi_pointer_array_get_size(&ompi_mpi_communicators)) {
-        return MPI_COMM_NULL;
+        return NULL;
     }
         
     return ompi_pointer_array_get_item(&ompi_mpi_communicators, o_index);
diff --git a/ompi/mpi/c/errhandler_f2c.c b/ompi/mpi/c/errhandler_f2c.c
index 6c266d063d..92f95f7bdc 100644
--- a/ompi/mpi/c/errhandler_f2c.c
+++ b/ompi/mpi/c/errhandler_f2c.c
@@ -9,6 +9,7 @@
  *                         University of Stuttgart.  All rights reserved.
  * Copyright (c) 2004-2005 The Regents of the University of California.
  *                         All rights reserved.
+ * Copyright (c) 2006      Cisco Systems, Inc.  All rights reserved.
  * $COPYRIGHT$
  * 
  * Additional copyrights may follow
@@ -43,12 +44,13 @@ MPI_Errhandler MPI_Errhandler_f2c(MPI_Fint errhandler_f)
     }
         
     /* Per MPI-2:4.12.4, do not invoke an error handler if we get an
-       invalid fortran handle */
-    
+       invalid fortran handle.  If we get an invalid fortran handle,
+       return an invalid C handle. */
+
     if (eh_index < 0 || 
         eh_index >= 
         ompi_pointer_array_get_size(ompi_errhandler_f_to_c_table)) {
-        return MPI_ERRHANDLER_NULL;
+        return NULL;
     }
 
     return ompi_pointer_array_get_item(ompi_errhandler_f_to_c_table,
diff --git a/ompi/mpi/c/file_f2c.c b/ompi/mpi/c/file_f2c.c
index be1bdd80f3..f658f8c6eb 100644
--- a/ompi/mpi/c/file_f2c.c
+++ b/ompi/mpi/c/file_f2c.c
@@ -9,6 +9,7 @@
  *                         University of Stuttgart.  All rights reserved.
  * Copyright (c) 2004-2005 The Regents of the University of California.
  *                         All rights reserved.
+ * Copyright (c) 2006      Cisco Systems, Inc.  All rights reserved.
  * $COPYRIGHT$
  * 
  * Additional copyrights may follow
@@ -42,12 +43,13 @@ MPI_File MPI_File_f2c(MPI_Fint file_f)
     }
 
     /* Per MPI-2:4.12.4, do not invoke an error handler if we get an
-       invalid fortran handle */
+       invalid fortran handle.  If we get an invalid fortran handle,
+       return an invalid C handle. */
 
     if (file_index < 0 ||
         file_index >= 
         ompi_pointer_array_get_size(&ompi_file_f_to_c_table)) {
-        return MPI_FILE_NULL;
+        return NULL;
     }
 
     return ompi_pointer_array_get_item(&ompi_file_f_to_c_table, file_index);
diff --git a/ompi/mpi/c/group_f2c.c b/ompi/mpi/c/group_f2c.c
index 2a5d903a72..a8e3e9079e 100644
--- a/ompi/mpi/c/group_f2c.c
+++ b/ompi/mpi/c/group_f2c.c
@@ -9,6 +9,7 @@
  *                         University of Stuttgart.  All rights reserved.
  * Copyright (c) 2004-2005 The Regents of the University of California.
  *                         All rights reserved.
+ * Copyright (c) 2006      Cisco Systems, Inc.  All rights reserved.
  * $COPYRIGHT$
  * 
  * Additional copyrights may follow
@@ -42,12 +43,13 @@ MPI_Group MPI_Group_f2c(MPI_Fint group_f)
     }
 
     /* Per MPI-2:4.12.4, do not invoke an error handler if we get an
-       invalid fortran handle */
+       invalid fortran handle.  If we get an invalid fortran handle,
+       return an invalid C handle. */
 
     if (group_index < 0 ||
         group_index >=
         ompi_pointer_array_get_size(ompi_group_f_to_c_table)) {
-        return MPI_GROUP_NULL;
+        return NULL;
     }
 
     return ompi_pointer_array_get_item(ompi_group_f_to_c_table, group_index);
diff --git a/ompi/mpi/c/info_f2c.c b/ompi/mpi/c/info_f2c.c
index 81dae6853d..181195e307 100644
--- a/ompi/mpi/c/info_f2c.c
+++ b/ompi/mpi/c/info_f2c.c
@@ -9,6 +9,7 @@
  *                         University of Stuttgart.  All rights reserved.
  * Copyright (c) 2004-2005 The Regents of the University of California.
  *                         All rights reserved.
+ * Copyright (c) 2006      Cisco Systems, Inc.  All rights reserved.
  * $COPYRIGHT$
  * 
  * Additional copyrights may follow
@@ -50,12 +51,13 @@ MPI_Info MPI_Info_f2c(MPI_Fint info)
     }
 
     /* Per MPI-2:4.12.4, do not invoke an error handler if we get an
-       invalid fortran handle */
+       invalid fortran handle.  If we get an invalid fortran handle,
+       return an invalid C handle. */
     
     if (info_index < 0 || 
         info_index >= 
         ompi_pointer_array_get_size(&ompi_info_f_to_c_table)) {
-        return MPI_INFO_NULL;
+        return NULL;
     }
 
     return ompi_pointer_array_get_item(&ompi_info_f_to_c_table, info_index);
diff --git a/ompi/mpi/c/op_f2c.c b/ompi/mpi/c/op_f2c.c
index f7c3dcdf14..80f1b31654 100644
--- a/ompi/mpi/c/op_f2c.c
+++ b/ompi/mpi/c/op_f2c.c
@@ -9,6 +9,7 @@
  *                         University of Stuttgart.  All rights reserved.
  * Copyright (c) 2004-2005 The Regents of the University of California.
  *                         All rights reserved.
+ * Copyright (c) 2006      Cisco Systems, Inc.  All rights reserved.
  * $COPYRIGHT$
  * 
  * Additional copyrights may follow
@@ -43,12 +44,13 @@ MPI_Op MPI_Op_f2c(MPI_Fint op_f)
     }
     
     /* Per MPI-2:4.12.4, do not invoke an error handler if we get an
-       invalid fortran handle */
+       invalid fortran handle.  If we get an invalid fortran handle,
+       return an invalid C handle. */
     
     if (op_index < 0 || 
         op_index >= 
         ompi_pointer_array_get_size(ompi_op_f_to_c_table)) {
-        return MPI_OP_NULL;
+        return NULL;
     }
 
     return ompi_pointer_array_get_item(ompi_op_f_to_c_table, op_index);
diff --git a/ompi/mpi/c/request_f2c.c b/ompi/mpi/c/request_f2c.c
index efe6181f28..6633af171f 100644
--- a/ompi/mpi/c/request_f2c.c
+++ b/ompi/mpi/c/request_f2c.c
@@ -9,6 +9,7 @@
  *                         University of Stuttgart.  All rights reserved.
  * Copyright (c) 2004-2005 The Regents of the University of California.
  *                         All rights reserved.
+ * Copyright (c) 2006      Cisco Systems, Inc.  All rights reserved.
  * $COPYRIGHT$
  * 
  * Additional copyrights may follow
@@ -41,12 +42,13 @@ MPI_Request MPI_Request_f2c(MPI_Fint request)
     }
 
     /* Per MPI-2:4.12.4, do not invoke an error handler if we get an
-       invalid fortran handle */
+       invalid fortran handle.  If we get an invalid fortran handle,
+       return an invalid C handle. */
     
     if (request_index < 0 || 
         request_index >= 
         ompi_pointer_array_get_size(&ompi_request_f_to_c_table)) {
-        return MPI_REQUEST_NULL;
+        return NULL;
     }
 
     return ompi_pointer_array_get_item(&ompi_request_f_to_c_table,
diff --git a/ompi/mpi/c/type_f2c.c b/ompi/mpi/c/type_f2c.c
index 8bb69667c4..47632323ec 100644
--- a/ompi/mpi/c/type_f2c.c
+++ b/ompi/mpi/c/type_f2c.c
@@ -9,6 +9,7 @@
  *                         University of Stuttgart.  All rights reserved.
  * Copyright (c) 2004-2005 The Regents of the University of California.
  *                         All rights reserved.
+ * Copyright (c) 2006      Cisco Systems, Inc.  All rights reserved.
  * $COPYRIGHT$
  * 
  * Additional copyrights may follow
@@ -41,12 +42,13 @@ MPI_Datatype MPI_Type_f2c(MPI_Fint datatype)
     }
 
     /* Per MPI-2:4.12.4, do not invoke an error handler if we get an
-       invalid fortran handle */
+       invalid fortran handle.  If we get an invalid fortran handle,
+       return an invalid C handle. */
     
     if (datatype_index < 0 || 
         datatype_index >= 
         ompi_pointer_array_get_size(ompi_datatype_f_to_c_table)) {
-        return MPI_DATATYPE_NULL;
+        return NULL;
     }
 
     return ompi_pointer_array_get_item(ompi_datatype_f_to_c_table, datatype);
diff --git a/ompi/mpi/c/win_f2c.c b/ompi/mpi/c/win_f2c.c
index 03947a801c..2d18c7fe93 100644
--- a/ompi/mpi/c/win_f2c.c
+++ b/ompi/mpi/c/win_f2c.c
@@ -9,6 +9,7 @@
  *                         University of Stuttgart.  All rights reserved.
  * Copyright (c) 2004-2005 The Regents of the University of California.
  *                         All rights reserved.
+ * Copyright (c) 2006      Cisco Systems, Inc.  All rights reserved.
  * $COPYRIGHT$
  * 
  * Additional copyrights may follow
@@ -41,11 +42,12 @@ MPI_Win MPI_Win_f2c(MPI_Fint win)
     }
 
     /* Per MPI-2:4.12.4, do not invoke an error handler if we get an
-       invalid fortran handle */
+       invalid fortran handle.  If we get an invalid fortran handle,
+       return an invalid C handle. */
 
     if ( 0 > o_index ||
          o_index >= ompi_pointer_array_get_size(&ompi_mpi_windows)) {
-        return MPI_WIN_NULL;
+        return NULL;
     }
         
     return ompi_pointer_array_get_item(&ompi_mpi_windows, o_index);