diff --git a/py/mpconfig.h b/py/mpconfig.h
index 2c4169070d..d4a9f3c50c 100644
--- a/py/mpconfig.h
+++ b/py/mpconfig.h
@@ -70,25 +70,28 @@
 
 // A MicroPython object is a machine word having the following form:
 //  - xxxx...xxx1 : a small int, bits 1 and above are the value
-//  - xxxx...xx10 : a qstr, bits 2 and above are the value
+//  - xxxx...x010 : a qstr, bits 3 and above are the value
+//  - xxxx...x110 : an immediate object, bits 3 and above are the value
 //  - xxxx...xx00 : a pointer to an mp_obj_base_t (unless a fake object)
 #define MICROPY_OBJ_REPR_A (0)
 
 // A MicroPython object is a machine word having the following form:
 //  - xxxx...xx01 : a small int, bits 2 and above are the value
-//  - xxxx...xx11 : a qstr, bits 2 and above are the value
+//  - xxxx...x011 : a qstr, bits 3 and above are the value
+//  - xxxx...x111 : an immediate object, bits 3 and above are the value
 //  - xxxx...xxx0 : a pointer to an mp_obj_base_t (unless a fake object)
 #define MICROPY_OBJ_REPR_B (1)
 
 // A MicroPython object is a machine word having the following form (called R):
 //  - iiiiiiii iiiiiiii iiiiiiii iiiiiii1 small int with 31-bit signed value
-//  - 01111111 1qqqqqqq qqqqqqqq qqqqq110 str with 20-bit qstr value
+//  - 01111111 1qqqqqqq qqqqqqqq qqqq0110 str with 19-bit qstr value
+//  - 01111111 10000000 00000000 ssss1110 immediate object with 4-bit value
 //  - s1111111 10000000 00000000 00000010 +/- inf
 //  - s1111111 1xxxxxxx xxxxxxxx xxxxx010 nan, x != 0
 //  - seeeeeee efffffff ffffffff ffffff10 30-bit fp, e != 0xff
 //  - pppppppp pppppppp pppppppp pppppp00 ptr (4 byte alignment)
-// Str and float stored as O = R + 0x80800000, retrieved as R = O - 0x80800000.
-// This makes strs easier to encode/decode as they have zeros in the top 9 bits.
+// Str, immediate and float stored as O = R + 0x80800000, retrieved as R = O - 0x80800000.
+// This makes strs/immediates easier to encode/decode as they have zeros in the top 9 bits.
 // This scheme only works with 32-bit word size and float enabled.
 #define MICROPY_OBJ_REPR_C (2)
 
@@ -98,6 +101,7 @@
 //  - 01111111 11111000 00000000 00000000 00000000 00000000 00000000 00000000 normalised nan
 //  - 01111111 11111101 iiiiiiii iiiiiiii iiiiiiii iiiiiiii iiiiiiii iiiiiii1 small int
 //  - 01111111 11111110 00000000 00000000 qqqqqqqq qqqqqqqq qqqqqqqq qqqqqqq1 str
+//  - 01111111 11111111 ss000000 00000000 00000000 00000000 00000000 00000000 immediate object
 //  - 01111111 11111100 00000000 00000000 pppppppp pppppppp pppppppp pppppp00 ptr (4 byte alignment)
 // Stored as O = R + 0x8004000000000000, retrieved as R = O - 0x8004000000000000.
 // This makes pointers have all zeros in the top 32 bits.
diff --git a/py/obj.h b/py/obj.h
index d98a0470da..f0bb44a403 100644
--- a/py/obj.h
+++ b/py/obj.h
@@ -87,9 +87,14 @@ static inline bool mp_obj_is_small_int(mp_const_obj_t o)
 #define MP_OBJ_NEW_SMALL_INT(small_int) ((mp_obj_t)((((mp_uint_t)(small_int)) << 1) | 1))
 
 static inline bool mp_obj_is_qstr(mp_const_obj_t o)
-    { return ((((mp_int_t)(o)) & 3) == 2); }
-#define MP_OBJ_QSTR_VALUE(o) (((mp_uint_t)(o)) >> 2)
-#define MP_OBJ_NEW_QSTR(qst) ((mp_obj_t)((((mp_uint_t)(qst)) << 2) | 2))
+    { return ((((mp_int_t)(o)) & 7) == 2); }
+#define MP_OBJ_QSTR_VALUE(o) (((mp_uint_t)(o)) >> 3)
+#define MP_OBJ_NEW_QSTR(qst) ((mp_obj_t)((((mp_uint_t)(qst)) << 3) | 2))
+
+static inline bool mp_obj_is_immediate_obj(mp_const_obj_t o)
+    { return ((((mp_int_t)(o)) & 7) == 6); }
+#define MP_OBJ_IMMEDIATE_OBJ_VALUE(o) (((mp_uint_t)(o)) >> 3)
+#define MP_OBJ_NEW_IMMEDIATE_OBJ(val) ((mp_obj_t)(((val) << 3) | 6))
 
 #if MICROPY_PY_BUILTINS_FLOAT
 #define mp_const_float_e MP_ROM_PTR(&mp_const_float_e_obj)
@@ -113,9 +118,14 @@ static inline bool mp_obj_is_small_int(mp_const_obj_t o)
 #define MP_OBJ_NEW_SMALL_INT(small_int) ((mp_obj_t)((((mp_uint_t)(small_int)) << 2) | 1))
 
 static inline bool mp_obj_is_qstr(mp_const_obj_t o)
-    { return ((((mp_int_t)(o)) & 3) == 3); }
-#define MP_OBJ_QSTR_VALUE(o) (((mp_uint_t)(o)) >> 2)
-#define MP_OBJ_NEW_QSTR(qst) ((mp_obj_t)((((mp_uint_t)(qst)) << 2) | 3))
+    { return ((((mp_int_t)(o)) & 7) == 3); }
+#define MP_OBJ_QSTR_VALUE(o) (((mp_uint_t)(o)) >> 3)
+#define MP_OBJ_NEW_QSTR(qst) ((mp_obj_t)((((mp_uint_t)(qst)) << 3) | 3))
+
+static inline bool mp_obj_is_immediate_obj(mp_const_obj_t o)
+    { return ((((mp_int_t)(o)) & 7) == 7); }
+#define MP_OBJ_IMMEDIATE_OBJ_VALUE(o) (((mp_uint_t)(o)) >> 3)
+#define MP_OBJ_NEW_IMMEDIATE_OBJ(val) ((mp_obj_t)(((val) << 3) | 7))
 
 #if MICROPY_PY_BUILTINS_FLOAT
 #define mp_const_float_e MP_ROM_PTR(&mp_const_float_e_obj)
@@ -161,9 +171,14 @@ static inline mp_obj_t mp_obj_new_float(mp_float_t f) {
 #endif
 
 static inline bool mp_obj_is_qstr(mp_const_obj_t o)
-    { return (((mp_uint_t)(o)) & 0xff800007) == 0x00000006; }
-#define MP_OBJ_QSTR_VALUE(o) (((mp_uint_t)(o)) >> 3)
-#define MP_OBJ_NEW_QSTR(qst) ((mp_obj_t)((((mp_uint_t)(qst)) << 3) | 0x00000006))
+    { return (((mp_uint_t)(o)) & 0xff80000f) == 0x00000006; }
+#define MP_OBJ_QSTR_VALUE(o) (((mp_uint_t)(o)) >> 4)
+#define MP_OBJ_NEW_QSTR(qst) ((mp_obj_t)((((mp_uint_t)(qst)) << 4) | 0x00000006))
+
+static inline bool mp_obj_is_immediate_obj(mp_const_obj_t o)
+    { return (((mp_uint_t)(o)) & 0xff80000f) == 0x0000000e; }
+#define MP_OBJ_IMMEDIATE_OBJ_VALUE(o) (((mp_uint_t)(o)) >> 4)
+#define MP_OBJ_NEW_IMMEDIATE_OBJ(val) ((mp_obj_t)(((val) << 4) | 0xe))
 
 static inline bool mp_obj_is_obj(mp_const_obj_t o)
     { return ((((mp_int_t)(o)) & 3) == 0); }
@@ -180,6 +195,11 @@ static inline bool mp_obj_is_qstr(mp_const_obj_t o)
 #define MP_OBJ_QSTR_VALUE(o) ((((uint32_t)(o)) >> 1) & 0xffffffff)
 #define MP_OBJ_NEW_QSTR(qst) ((mp_obj_t)(((uint64_t)(((uint32_t)(qst)) << 1)) | 0x0002000000000001))
 
+static inline bool mp_obj_is_immediate_obj(mp_const_obj_t o)
+    { return ((((uint64_t)(o)) & 0xffff000000000000) == 0x0003000000000000); }
+#define MP_OBJ_IMMEDIATE_OBJ_VALUE(o) ((((uint32_t)(o)) >> 46) & 3)
+#define MP_OBJ_NEW_IMMEDIATE_OBJ(val) (((uint64_t)(val) << 46) | 0x0003000000000000)
+
 #if MICROPY_PY_BUILTINS_FLOAT
 
 #if MICROPY_FLOAT_IMPL != MICROPY_FLOAT_IMPL_DOUBLE