diff --git a/m-array.h b/m-array.h
index 71acecdb..3cf51da4 100644
--- a/m-array.h
+++ b/m-array.h
@@ -76,6 +76,7 @@
    ,IT_INSERT(M_C(name,_insert))                                        \
    ,IT_REMOVE(M_C(name,_remove))                                        \
    ,CLEAN(M_C(name,_clean))						\
+   ,KEY_TYPE(size_t)                                                    \
    ,SET_KEY(M_C(name, _set_at))                                         \
    ,GET_KEY(M_C(name, _get))                                            \
    ,M_IF_METHOD(INIT, oplist)(GET_SET_KEY(M_C(name, _get_at)) ,)        \
diff --git a/m-bptree.h b/m-bptree.h
index 05384538..32d9bea3 100644
--- a/m-bptree.h
+++ b/m-bptree.h
@@ -80,6 +80,7 @@
    CLEAN(M_C(name,_clean)),						\
    GET_MIN(M_C(name,_min)),						\
    GET_MAX(M_C(name,_max)),						\
+   KEY_TYPE(M_C(name, _key_type_t)),                                    \
    SET_KEY(M_C(name, _set_at)),                                         \
    GET_KEY(M_C(name, _get)),                                            \
    /*GET_SET_KEY(M_C(name, _get_at))*/,                                 \
@@ -185,6 +186,8 @@
               ,                                                         \
               typedef key_t M_C(name, _type_t);                         \
                                                                         ) \
+  typedef key_t M_C(name, _key_type_t);                                 \
+  typedef value_t M_C(name, _value_type_t);                             \
                                                                         \
   /* Node of a B+TREE */                                                \
   typedef struct M_C(name, _node_s) {                                   \
diff --git a/m-core.h b/m-core.h
index 805dbd53..18bd7fe8 100644
--- a/m-core.h
+++ b/m-core.h
@@ -1784,6 +1784,7 @@ m_core_hash (const void *str, size_t length)
 #define M_MUL_MUL(a)             ,a,
 #define M_DIV_DIV(a)             ,a,
 #define M_CLEAN_CLEAN(a)         ,a,
+#define M_KEY_TYPE_KEY_TYPE(a)   ,a,
 #define M_GET_KEY_GET_KEY(a)     ,a,
 #define M_SET_KEY_SET_KEY(a)     ,a,
 #define M_GET_SET_KEY_GET_SET_KEY(a) ,a,
@@ -1855,6 +1856,7 @@ m_core_hash (const void *str, size_t length)
 #define M_GET_MUL(...)       M_GET_METHOD(MUL,         M_MUL_DEFAULT,      __VA_ARGS__)
 #define M_GET_DIV(...)       M_GET_METHOD(DIV,         M_DIV_DEFAULT,      __VA_ARGS__)
 #define M_GET_CLEAN(...)     M_GET_METHOD(CLEAN,       M_NO_DEFAULT,       __VA_ARGS__)
+#define M_GET_KEY_TYPE(...)  M_GET_METHOD(KEY_TYPE,    M_NO_DEFAULT,       __VA_ARGS__)
 #define M_GET_GET_KEY(...)   M_GET_METHOD(GET_KEY,     M_NO_DEFAULT,       __VA_ARGS__)
 #define M_GET_SET_KEY(...)   M_GET_METHOD(SET_KEY,     M_NO_DEFAULT,       __VA_ARGS__)
 #define M_GET_GET_SET_KEY(...) M_GET_METHOD(GET_SET_KEY, M_NO_DEFAULT,     __VA_ARGS__)
diff --git a/m-dict.h b/m-dict.h
index 36911d7e..4ea208b9 100644
--- a/m-dict.h
+++ b/m-dict.h
@@ -190,8 +190,11 @@
     size_t used, lower_limit, upper_limit;                              \
     M_C(name, _array_list_pair_t) table;				\
   } dict_t[1];                                                          \
+                                                                        \
   typedef struct M_C(name, _s) *M_C(name, _ptr);                        \
   typedef const struct M_C(name, _s) *M_C(name, _srcptr);               \
+  typedef key_type M_C(name, _key_type_t);                              \
+  typedef value_type M_C(name, _value_type_t);                          \
                                                                         \
   typedef struct M_C(name, _it_s) {					\
     M_C(name, _array_list_pair_it_t) array_it;				\
@@ -800,6 +803,7 @@
    IT_NEXT(M_C(name,_next)),						\
    IT_REF(M_C(name,_ref)),						\
    IT_CREF(M_C(name,_cref))						\
+   ,KEY_TYPE(M_C(name, _key_type_t))                                    \
    ,SET_KEY(M_C(name, _set_at))                                         \
    ,GET_KEY(M_C(name, _get))                                            \
    ,GET_SET_KEY(M_C(name, _get_at))                                     \