diff --git a/src/mpi/c/attr_fn.c b/src/mpi/c/attr_fn.c
index 0c2311d328..ef24d93c47 100644
--- a/src/mpi/c/attr_fn.c
+++ b/src/mpi/c/attr_fn.c
@@ -10,71 +10,100 @@
 #include "communicator/communicator.h"
 #include "win/win.h"
 
-int MPI_TYPE_NULL_DELETE_FN( MPI_Datatype datatype, int type_keyval,
-                             void* attribute_val_out,
-                             void* flag )
+/*
+ * Note that these are the back-end functions for MPI_DUP_FN (and
+ * friends).  They have an OMPI_C_* prefix because of weird reasons
+ * listed in a lengthy comment in mpi.h.
+ *
+ * Specifically:
+ *
+ *   MPI_NULL_DELETE_FN -> OMPI_C_MPI_NULL_DELETE_FN
+ *   MPI_NULL_COPY_FN -> OMPI_C_MPI_NULL_COPY_FN
+ *   MPI_DUP_FN -> OMPI_C_MPI_DUP_FN
+ *
+ *   MPI_TYPE_NULL_DELETE_FN -> OMPI_C_MPI_TYPE_NULL_DELETE_FN
+ *   MPI_TYPE_NULL_COPY_FN -> OMPI_C_MPI_TYPE_NULL_COPY_FN
+ *   MPI_TYPE_DUP_FN -> OMPI_C_MPI_TYPE_DUP_FN
+ *
+ *   MPI_COMM_NULL_DELETE_FN -> OMPI_C_MPI_COMM_NULL_DELETE_FN
+ *   MPI_COMM_NULL_COPY_FN -> OMPI_C_MPI_COMM_NULL_COPY_FN
+ *   MPI_COMM_DUP_FN -> OMPI_C_MPI_COMM_DUP_FN
+ *
+ *   MPI_WIN_NULL_DELETE_FN -> OMPI_C_MPI_WIN_NULL_DELETE_FN
+ *   MPI_WIN_NULL_COPY_FN -> OMPI_C_MPI_WIN_NULL_COPY_FN
+ *   MPI_WIN_DUP_FN -> OMPI_C_MPI_WIN_DUP_FN
+ */
+
+int OMPI_C_MPI_TYPE_NULL_DELETE_FN( MPI_Datatype datatype, int type_keyval,
+                                    void* attribute_val_out,
+                                    void* flag )
 {
    /* Why not all MPI functions are like this ?? */
    return MPI_SUCCESS;
 }
 
-int MPI_TYPE_NULL_COPY_FN( MPI_Datatype datatype, int type_keyval, void* extra_state,
-                           void* attribute_val_in, void* attribute_val_out,
-                           int* flag )
+int OMPI_C_MPI_TYPE_NULL_COPY_FN( MPI_Datatype datatype, int type_keyval, 
+                                  void* extra_state,
+                                  void* attribute_val_in, 
+                                  void* attribute_val_out,
+                                  int* flag )
 {
    *flag = 0;
    return MPI_SUCCESS;
 }
 
-int MPI_TYPE_DUP_FN( MPI_Datatype datatype, int type_keyval, void* extra_state,
-                     void* attribute_val_in, void* attribute_val_out,
-                     int* flag )
+int OMPI_C_MPI_TYPE_DUP_FN( MPI_Datatype datatype, int type_keyval, 
+                            void* extra_state,
+                            void* attribute_val_in, void* attribute_val_out,
+                            int* flag )
 {
    *flag = 1;
    *(void**)attribute_val_out = attribute_val_in;
    return MPI_SUCCESS;
 }
 
-int MPI_WIN_NULL_DELETE_FN( MPI_Win window, int win_keyval,
-                            void* attribute_val_out,
-                            void* flag )
+int OMPI_C_MPI_WIN_NULL_DELETE_FN( MPI_Win window, int win_keyval,
+                                   void* attribute_val_out,
+                                   void* flag )
 {
    return MPI_SUCCESS;
 }
 
-int MPI_WIN_NULL_COPY_FN( MPI_Win window, int win_keyval, void* extra_state,
-                          void* attribute_val_in, void* attribute_val_out,
-                          int* flag )
+int OMPI_C_MPI_WIN_NULL_COPY_FN( MPI_Win window, int win_keyval, 
+                                 void* extra_state,
+                                 void* attribute_val_in,
+                                 void* attribute_val_out, int* flag )
 {
    *flag= 0;
    return MPI_SUCCESS;
 }
 
-int MPI_WIN_DUP_FN( MPI_Win window, int win_keyval, void* extra_state,
-                    void* attribute_val_in, void* attribute_val_out,
-                    int* flag )
-{
-   *flag = 1;
-   *(void**)attribute_val_out = attribute_val_in;
-   return MPI_SUCCESS;
-}
-
-int MPI_COMM_NULL_DELETE_FN( MPI_Comm comm, int comm_keyval,
-                             void* attribute_val_out,
-                             void* flag )
-{
-   return MPI_SUCCESS;
-}
-
-int MPI_COMM_NULL_COPY_FN( MPI_Comm comm, int comm_keyval, void* extra_state,
+int OMPI_C_MPI_WIN_DUP_FN( MPI_Win window, int win_keyval, void* extra_state,
                            void* attribute_val_in, void* attribute_val_out,
                            int* flag )
+{
+   *flag = 1;
+   *(void**)attribute_val_out = attribute_val_in;
+   return MPI_SUCCESS;
+}
+
+int OMPI_C_MPI_COMM_NULL_DELETE_FN( MPI_Comm comm, int comm_keyval,
+                                    void* attribute_val_out,
+                                    void* flag )
+{
+   return MPI_SUCCESS;
+}
+
+int OMPI_C_MPI_COMM_NULL_COPY_FN( MPI_Comm comm, int comm_keyval, 
+                                  void* extra_state,
+                                  void* attribute_val_in,
+                                  void* attribute_val_out, int* flag )
 {
    *flag= 0;
    return MPI_SUCCESS;
 }
 
-int MPI_COMM_DUP_FN( MPI_Comm comm, int comm_keyval, void* extra_state,
+int OMPI_C_MPI_COMM_DUP_FN( MPI_Comm comm, int comm_keyval, void* extra_state,
                      void* attribute_val_in, void* attribute_val_out,
                      int* flag )
 {
@@ -83,24 +112,24 @@ int MPI_COMM_DUP_FN( MPI_Comm comm, int comm_keyval, void* extra_state,
    return MPI_SUCCESS;
 }
 
-int MPI_NULL_DELETE_FN( MPI_Comm comm, int comm_keyval,
-                        void* attribute_val_out,
-                        void* flag )
+int OMPI_C_MPI_NULL_DELETE_FN( MPI_Comm comm, int comm_keyval,
+                               void* attribute_val_out,
+                               void* flag )
 {
    return MPI_SUCCESS;
 }
 
-int MPI_NULL_COPY_FN( MPI_Comm comm, int comm_keyval, void* extra_state,
-                      void* attribute_val_in, void* attribute_val_out,
-                      int* flag )
+int OMPI_C_MPI_NULL_COPY_FN( MPI_Comm comm, int comm_keyval, void* extra_state,
+                             void* attribute_val_in, void* attribute_val_out,
+                             int* flag )
 {
    *flag= 0;
    return MPI_SUCCESS;
 }
 
-int MPI_DUP_FN( MPI_Comm comm, int comm_keyval, void* extra_state,
-                void* attribute_val_in, void* attribute_val_out,
-                int* flag )
+int OMPI_C_MPI_DUP_FN( MPI_Comm comm, int comm_keyval, void* extra_state,
+                       void* attribute_val_in, void* attribute_val_out,
+                       int* flag )
 {
    *flag = 1;
    *(void**)attribute_val_out = attribute_val_in;
diff --git a/src/mpi/f77/attr_fn_f.c b/src/mpi/f77/attr_fn_f.c
index f3e3cdc0f8..555e3a3905 100644
--- a/src/mpi/f77/attr_fn_f.c
+++ b/src/mpi/f77/attr_fn_f.c
@@ -148,6 +148,29 @@ OMPI_GENERATE_F77_BINDINGS( MPI_WIN_DUP_FN,
                             (window, win_keyval, extra_state, attribute_val_in, attribute_val_out, flag, ierr) )
 #endif
 
+/*
+ * Note that in this file, we invoke OMPI_C_<function> rather than
+ * <function>, where <function> is MPI_DUP_FN (and all the rest).
+ * Specifically:
+ * 
+ *   MPI_NULL_DELETE_FN -> OMPI_C_MPI_NULL_DELETE_FN
+ *   MPI_NULL_COPY_FN -> OMPI_C_MPI_NULL_COPY_FN
+ *   MPI_DUP_FN -> OMPI_C_MPI_DUP_FN
+ *
+ *   MPI_TYPE_NULL_DELETE_FN -> OMPI_C_MPI_TYPE_NULL_DELETE_FN
+ *   MPI_TYPE_NULL_COPY_FN -> OMPI_C_MPI_TYPE_NULL_COPY_FN
+ *   MPI_TYPE_DUP_FN -> OMPI_C_MPI_TYPE_DUP_FN
+ *
+ *   MPI_COMM_NULL_DELETE_FN -> OMPI_C_MPI_COMM_NULL_DELETE_FN
+ *   MPI_COMM_NULL_COPY_FN -> OMPI_C_MPI_COMM_NULL_COPY_FN
+ *   MPI_COMM_DUP_FN -> OMPI_C_MPI_COMM_DUP_FN
+ *
+ *   MPI_WIN_NULL_DELETE_FN -> OMPI_C_MPI_WIN_NULL_DELETE_FN
+ *   MPI_WIN_NULL_COPY_FN -> OMPI_C_MPI_WIN_NULL_COPY_FN
+ *   MPI_WIN_DUP_FN -> OMPI_C_MPI_WIN_DUP_FN
+ *
+ * The reason why is discussed in a lengthy comment in mpi.h.
+ */
 void mpi_type_null_delete_fn_f( MPI_Fint* type, int* type_keyval,
                                 void* attribute_val_out, int* flag, int* ierr )
 {