diff --git a/ompi/datatype/datatype.h b/ompi/datatype/datatype.h
index f6e6974a6b..761654e314 100644
--- a/ompi/datatype/datatype.h
+++ b/ompi/datatype/datatype.h
@@ -59,10 +59,12 @@ OMPI_DECLSPEC extern ompi_pointer_array_t *ompi_datatype_f_to_c_table;
 #define DT_FLAG_USER_LB       0x0010  /**< has a user defined LB */
 #define DT_FLAG_USER_UB       0x0020  /**< has a user defined UB */
 #define DT_FLAG_PREDEFINED    0x0040  /**< cannot be removed: initial and predefined datatypes */
-#define DT_FLAG_IN_LOOP       0x0080  /**< we are inside a loop */
+#define DT_FLAG_NO_GAPS       0x0080  /**< we are inside a loop */
 #define DT_FLAG_DATA          0x0100  /**< data or control structure */
 #define DT_FLAG_ONE_SIDED     0x0200  /**< datatype can be used for one sided operations */
-#define DT_FLAG_UNAVAILABLE   0x0400  /**< datatypes unavailable on thie build (OS or compiler dependant) */
+#define DT_FLAG_UNAVAILABLE   0x0400  /**< datatypes unavailable on the build (OS or compiler dependant) */
+#define DT_FLAG_VECTOR        0x0800  /**< valid only for loops. The loop contain only one element
+                                       **< without extent. It correspond to the vector type. */
 /* Keep trace of the type of the predefined datatypes */
 #define DT_FLAG_DATA_INT      0x1000
 #define DT_FLAG_DATA_FLOAT    0x2000
@@ -78,7 +80,7 @@ OMPI_DECLSPEC extern ompi_pointer_array_t *ompi_datatype_f_to_c_table;
  * We should make the difference here between the predefined contiguous and non contiguous
  * datatypes. The DT_FLAG_BASIC is held by all predefined contiguous datatypes.
  */
-#define DT_FLAG_BASIC         (DT_FLAG_PREDEFINED | DT_FLAG_CONTIGUOUS | DT_FLAG_DATA | DT_FLAG_COMMITED)
+#define DT_FLAG_BASIC         (DT_FLAG_PREDEFINED | DT_FLAG_CONTIGUOUS | DT_FLAG_NO_GAPS | DT_FLAG_DATA | DT_FLAG_COMMITED)
 
 typedef union dt_elem_desc dt_elem_desc_t;
 
diff --git a/ompi/datatype/dt_add.c b/ompi/datatype/dt_add.c
index 5ef6513c49..924ca93964 100644
--- a/ompi/datatype/dt_add.c
+++ b/ompi/datatype/dt_add.c
@@ -23,7 +23,8 @@
 
 /* macros to play with the flags */
 #define SET_CONTIGUOUS_FLAG( INT_VALUE )     (INT_VALUE) = (INT_VALUE) | (DT_FLAG_CONTIGUOUS)
-#define UNSET_CONTIGUOUS_FLAG( INT_VALUE )   (INT_VALUE) = (INT_VALUE) & (~(DT_FLAG_CONTIGUOUS))
+#define SET_NO_GAP_FLAG( INT_VALUE )         (INT_VALUE) = (INT_VALUE) | (DT_FLAG_NO_GAPS)
+#define UNSET_CONTIGUOUS_FLAG( INT_VALUE )   (INT_VALUE) = (INT_VALUE) & (~(DT_FLAG_CONTIGUOUS | DT_FLAG_NO_GAPS))
 
 #if defined(__GNUC__) && !defined(__STDC__)
 #define LMAX(A,B)  ({ long _a = (A), _b = (B); (_a < _b ? _b : _a) })
@@ -259,7 +260,6 @@ int32_t ompi_ddt_add( ompi_datatype_t* pdtBase, const ompi_datatype_t* pdtAdd,
                 pLoop = pLast;
                 CREATE_LOOP_START( pLast, count, (long)pdtAdd->desc.used + 1, extent,
                                    (pdtAdd->flags & ~(DT_FLAG_COMMITED)) );
-                localFlags = DT_FLAG_IN_LOOP;
                 pdtBase->btypes[DT_LOOP] += 2;
                 pdtBase->desc.used += 2;
                 pLast++;
@@ -267,7 +267,6 @@ int32_t ompi_ddt_add( ompi_datatype_t* pdtBase, const ompi_datatype_t* pdtAdd,
 
             for( i = 0; i < pdtAdd->desc.used; i++ ) {
                 pLast->elem               = pdtAdd->desc.desc[i].elem;
-                pLast->elem.common.flags |= localFlags;
                 if( DT_FLAG_DATA & pLast->elem.common.flags )
                     pLast->elem.disp += disp;
                 else if( DT_END_LOOP == pLast->elem.common.type ) {
@@ -302,9 +301,13 @@ int32_t ompi_ddt_add( ompi_datatype_t* pdtBase, const ompi_datatype_t* pdtAdd,
                                                     * type have to match */
                  || (count < 2)) ) {               /*  - if the count is bigger than 2 */
             SET_CONTIGUOUS_FLAG(pdtBase->flags);
+            if( ((long)pdtAdd->size) == extent )
+                SET_NO_GAP_FLAG(pdtBase->flags);
         }
     }
-
+    /* If the NO_GAP flag is set the contiguous have to be set too */
+    if( pdtBase->flags & DT_FLAG_NO_GAPS )
+        assert( pdtBase->flags & DT_FLAG_CONTIGUOUS );
     pdtBase->nbElems += (count * pdtAdd->nbElems);
 
     return OMPI_SUCCESS;
diff --git a/ompi/datatype/dt_module.c b/ompi/datatype/dt_module.c
index a245966b9c..be543fffce 100644
--- a/ompi/datatype/dt_module.c
+++ b/ompi/datatype/dt_module.c
@@ -654,7 +654,7 @@ static int _dump_data_flags( unsigned short usflags, char* ptr, size_t length )
     if( usflags & DT_FLAG_USER_LB )                  ptr[4]  = 'l';
     if( usflags & DT_FLAG_USER_UB )                  ptr[5]  = 'u';
     if( usflags & DT_FLAG_PREDEFINED )               ptr[6]  = 'P';
-    if( usflags & DT_FLAG_IN_LOOP )                  ptr[7]  = 'L';
+    if( !(usflags & DT_FLAG_NO_GAPS) )               ptr[7]  = 'G';
     if( usflags & DT_FLAG_DATA )                     ptr[8]  = 'D';
     if( (usflags & DT_FLAG_BASIC) == DT_FLAG_BASIC ) ptr[9]  = 'B';
     /* Which kind of datatype is that */