diff --git a/m-core.h b/m-core.h
index 82278128..068d6877 100644
--- a/m-core.h
+++ b/m-core.h
@@ -4438,22 +4438,23 @@ m_core_parse2_enum (const char str[], const char **endptr)
   M_BY_NARGS( M_IF(M_GET_PROPERTY(oplist, NOCLEAR))(M_CHAIN_OBJ_A, M_CHAIN_OBJ_B), __VA_ARGS__) \
   (name, oplist, __VA_ARGS__)
 // Need to define an exception handler. Use of M_CHAIN_INIT
-#define M_CHAIN_OBJ_B__NARGS_1(name, oplist, var)                             \
+#define M_CHAIN_OBJ_B__1(name, oplist, var)                             \
   M_CHAIN_INIT( name, M_CALL_INIT(oplist, var), M_CALL_CLEAR(oplist, var) )
-#define M_CHAIN_OBJ_B__NARGS_2(name, oplist, var, value)                      \
-  M_IF(M_PARENTHESIS_P(value))(M_CHAIN_OBJ_B__NARGS_2_WITH, M_CHAIN_OBJ_B__NARGS_2_SET) \
+#define M_CHAIN_OBJ_B__2(name, oplist, var, value)                      \
+  M_IF(M_PARENTHESIS_P(value))(M_CHAIN_OBJ_B__2_WITH, M_CHAIN_OBJ_B__2_SET) \
   (name, oplist, var, value)
-#define M_CHAIN_OBJ_B__NARGS_2_WITH(name, oplist, var, value)                 \
+#define M_CHAIN_OBJ_B__2_WITH(name, oplist, var, value)                 \
   M_CHAIN_INIT( name, M_CALL_INIT_WITH(oplist, var, value), M_CALL_CLEAR(oplist, var) )
-#define M_CHAIN_OBJ_B__NARGS_2_SET(name, oplist, var, value)                  \
+#define M_CHAIN_OBJ_B__2_SET(name, oplist, var, value)                  \
   M_CHAIN_INIT( name, M_CALL_INIT_SET(oplist, var, value), M_CALL_CLEAR(oplist, var) )
 // No need to define an exception handler. Just call the INIT function.
-#define M_CHAIN_OBJ_A__NARGS_1(name, oplist, var)                             \
+#define M_CHAIN_OBJ_A__1(name, oplist, var)                             \
   M_CHAIN_FOR(name, M_CALL_INIT(oplist, var) )
-#define M_CHAIN_OBJ_A__NARGS_2(name, oplist, var, value)                      \
+#define M_CHAIN_OBJ_A__2(name, oplist, var, value)                      \
   M_CHAIN_FOR(name,                                                           \
       M_IF(M_PARENTHESIS_P(value))(M_CALL_INIT_WITH, M_CALL_INIT_SET)         \
       (oplist, var, value) )
+
 // Execute the 'init' function in a for loop construct
 #define M_CHAIN_FOR(name,  init )                                             \
   M_CHAIN_FOR_B(M_C(m_var_, name), init)
@@ -4513,17 +4514,18 @@ m_core_parse2_enum (const char str[], const char **endptr)
 /******************* INIT_WITH Enhancing ********************/
 /************************************************************/
 
-/* Add as suffix for the given function the number of arguments of the calls.
+/* Add as suffix for the given function the number of arguments of the calls
+   equal to __ # NARGS(...)
    Can be used to call different function in function of the number of arguments.
    It doesn't call the function with the argument in order to be able to chain the 
    macro */
-#define M_BY_NARGS(function, ...) M_C3(function, __NARGS_, M_NARGS(__VA_ARGS__))
+#define M_BY_NARGS(function, ...) M_C3(function, __, M_NARGS(__VA_ARGS__))
 
-/* Call different INIT_WITH method in function of the number of arguments of the call,
- * to be used in an OPLIST.
+/* Call different methods in function of the number of arguments of the call,
+ * to be used in an OPLIST for the INIT_WITH operator.
  * Shall be used with API_1 call (example INIT_WITH(API_1(M_INIT_WITH_NVAR)) )
  * Shall define a NAME base method
- * All INIT_WITH methods shall be named as name ## _init_with_ ## NARGS
+ * All INIT_WITH methods shall be named as name ## _init_with__ ## NARGS
  */
 #define M_INIT_WITH_NVAR(oplist, ...)                                         \
   M_BY_NARGS(M_C(M_GET_NAME oplist, _init_with), __VA_ARGS__)(__VA_ARGS__)
diff --git a/m-worker.h b/m-worker.h
index 6bae1c8f..e7393599 100644
--- a/m-worker.h
+++ b/m-worker.h
@@ -188,11 +188,11 @@ typedef struct m_worker_sync_s {
    input is (fieldname, type) or (fieldname, type, oplist)
    Output shall be : M_OPEXTEND(M_GLOBAL_OPLIST_OR_DEF(type_or_oplist)(), TYPE(type)) / M_OPEXTEND(oplist, TYPE(type))
  */
-#define M_WORK3R_SPAWN_EXTEND_P0(...)                   M_BY_NARGS(M_WORK3R_SPAWN_EXTEND_P0, M_ID __VA_ARGS__) __VA_ARGS__
-#define M_WORK3R_SPAWN_EXTEND_P0__NARGS_2(field, type)         M_OPEXTEND(M_GLOBAL_OPLIST_OR_DEF(type)(), TYPE(type))
-#define M_WORK3R_SPAWN_EXTEND_P0__NARGS_3(field, type, oplist) M_IF_OPLIST(oplist)(M_WORK3R_SPAWN_EXTEND_P0__NARGS_3_OK, M_WORK3R_SPAWN_EXTEND_P0__NARGS_3_KO)(field, type, oplist)
-#define M_WORK3R_SPAWN_EXTEND_P0__NARGS_3_OK(field, type, oplist) M_OPEXTEND(oplist, TYPE(type))
-#define M_WORK3R_SPAWN_EXTEND_P0__NARGS_3_KO(field, type, oplist)             \
+#define M_WORK3R_SPAWN_EXTEND_P0(...)                       M_BY_NARGS(M_WORK3R_SPAWN_EXTEND_P0, M_ID __VA_ARGS__) __VA_ARGS__
+#define M_WORK3R_SPAWN_EXTEND_P0__2(field, type)            M_OPEXTEND(M_GLOBAL_OPLIST_OR_DEF(type)(), TYPE(type))
+#define M_WORK3R_SPAWN_EXTEND_P0__3(field, type, oplist)    M_IF_OPLIST(oplist)(M_WORK3R_SPAWN_EXTEND_P0__3_OK, M_WORK3R_SPAWN_EXTEND_P0__3_KO)(field, type, oplist)
+#define M_WORK3R_SPAWN_EXTEND_P0__3_OK(field, type, oplist) M_OPEXTEND(oplist, TYPE(type))
+#define M_WORK3R_SPAWN_EXTEND_P0__3_KO(field, type, oplist)             \
   M_STATIC_FAILURE(M_LIB_NOT_AN_OPLIST, "(M_WORKER_SPAWN_EXTEND): the argument is not a valid oplist: " M_MAP(M_AS_STR, oplist))
 
 /* Deferred evaluation for the definition,
diff --git a/tests/test-mcore.c b/tests/test-mcore.c
index f403131d..4f6bf7ff 100644
--- a/tests/test-mcore.c
+++ b/tests/test-mcore.c
@@ -570,8 +570,8 @@ static void test_oplist(void)
   assert (M_ID (M_GET_NAME A5));
 
 #define A6  (NAME(A6), INIT_WITH(API_1(M_INIT_WITH_NVAR)))
-#define A6_init_with__NARGS_1(x) 1
-#define A6_init_with__NARGS_2(x, y) 0
+#define A6_init_with__1(x) 1
+#define A6_init_with__2(x, y) 0
   assert (M_ID(M_CALL_INIT_WITH (A6, 0)));
   assert (M_ID(!M_CALL_INIT_WITH (A6, 0, 0)));
 }