diff --git a/Include/object.h b/Include/object.h
--- a/Include/object.h
+++ b/Include/object.h
@@ -413,7 +413,11 @@
     struct _typeobject *tp_next;
 #endif
 #ifdef STACKLESS
-    /* we need the extended structure right here */
+    /* we need this stuff from PyHeapTypeObject
+     * here in PyTypeObject so that the offset of
+     * the slpflags from the start is the same for PyTypeObject
+     * and PyHeapTypeObject
+     */
     PyNumberMethods as_number;
     PyMappingMethods as_mapping;
     PySequenceMethods as_sequence; /* as_sequence comes after as_mapping,
@@ -423,25 +427,112 @@
                                       see add_operators() in typeobject.c . */
     PyBufferProcs as_buffer;
     PyObject *ht_name, *ht_slots;
+    /* add this at the end, for binary compatibility */
     slp_methodflags slpflags;
 #endif
 } PyTypeObject;
 
+#ifdef STACKLESS
+/* need the un-extended type here to be part of the PyHeapTypeObject */
+typedef struct _basetypeobject {
+    PyObject_VAR_HEAD
+    const char *tp_name; /* For printing, in format "<module>.<name>" */
+    Py_ssize_t tp_basicsize, tp_itemsize; /* For allocation */
 
-#ifdef STACKLESS
+    /* Methods to implement standard operations */
 
-/* in Stackless, this is just a synonym */
-#define PyHeapTypeObject PyTypeObject
+    destructor tp_dealloc;
+    printfunc tp_print;
+    getattrfunc tp_getattr;
+    setattrfunc tp_setattr;
+    cmpfunc tp_compare;
+    reprfunc tp_repr;
 
-#define PyHeapType_GET_MEMBERS(etype) \
-    ((PyMemberDef *)(((char *)etype) + (etype)->ob_type->tp_basicsize))
-#else
+    /* Method suites for standard classes */
+
+    PyNumberMethods *tp_as_number;
+    PySequenceMethods *tp_as_sequence;
+    PyMappingMethods *tp_as_mapping;
+
+    /* More standard operations (here for binary compatibility) */
+
+    hashfunc tp_hash;
+    ternaryfunc tp_call;
+    reprfunc tp_str;
+    getattrofunc tp_getattro;
+    setattrofunc tp_setattro;
+
+    /* Functions to access object as input/output buffer */
+    PyBufferProcs *tp_as_buffer;
+
+    /* Flags to define presence of optional/expanded features */
+    long tp_flags;
+
+    const char *tp_doc; /* Documentation string */
+
+    /* Assigned meaning in release 2.0 */
+    /* call function for all accessible objects */
+    traverseproc tp_traverse;
+
+    /* delete references to contained objects */
+    inquiry tp_clear;
+
+    /* Assigned meaning in release 2.1 */
+    /* rich comparisons */
+    richcmpfunc tp_richcompare;
+
+    /* weak reference enabler */
+    Py_ssize_t tp_weaklistoffset;
+
+    /* Added in release 2.2 */
+    /* Iterators */
+    getiterfunc tp_iter;
+    iternextfunc tp_iternext;
+
+    /* Attribute descriptor and subclassing stuff */
+    struct PyMethodDef *tp_methods;
+    struct PyMemberDef *tp_members;
+    struct PyGetSetDef *tp_getset;
+    struct _typeobject *tp_base;
+    PyObject *tp_dict;
+    descrgetfunc tp_descr_get;
+    descrsetfunc tp_descr_set;
+    Py_ssize_t tp_dictoffset;
+    initproc tp_init;
+    allocfunc tp_alloc;
+    newfunc tp_new;
+    freefunc tp_free; /* Low-level free-memory routine */
+    inquiry tp_is_gc; /* For PyObject_IS_GC */
+    PyObject *tp_bases;
+    PyObject *tp_mro; /* method resolution order */
+    PyObject *tp_cache;
+    PyObject *tp_subclasses;
+    PyObject *tp_weaklist;
+    destructor tp_del;
+
+    /* Type attribute cache version tag. Added in version 2.6 */
+    unsigned int tp_version_tag;
+
+#ifdef COUNT_ALLOCS
+    /* these must be last and never explicitly initialized */
+    Py_ssize_t tp_allocs;
+    Py_ssize_t tp_frees;
+    Py_ssize_t tp_maxalloc;
+    struct _typeobject *tp_prev;
+    struct _typeobject *tp_next;
+#endif
+}PyBaseTypeObject;
+#endif /* STACKLESS */
 
 /* The *real* layout of a type object when allocated on the heap */
 typedef struct _heaptypeobject {
     /* Note: there's a dependency on the order of these members
        in slotptr() in typeobject.c . */
+#ifdef STACKLESS
+    PyBaseTypeObject ht_type;
+#else
     PyTypeObject ht_type;
+#endif
     PyNumberMethods as_number;
     PyMappingMethods as_mapping;
     PySequenceMethods as_sequence; /* as_sequence comes after as_mapping,
@@ -451,6 +542,9 @@
                                       see add_operators() in typeobject.c . */
     PyBufferProcs as_buffer;
     PyObject *ht_name, *ht_slots;
+#ifdef STACKLESS
+    slp_methodflags slpflags;
+#endif
     /* here are optional user slots, followed by the members. */
 } PyHeapTypeObject;
 
@@ -458,8 +552,6 @@
 #define PyHeapType_GET_MEMBERS(etype) \
     ((PyMemberDef *)(((char *)etype) + Py_TYPE(etype)->tp_basicsize))
 
-#endif
-
 /* Generic type check */
 PyAPI_FUNC(int) PyType_IsSubtype(PyTypeObject *, PyTypeObject *);
 #define PyObject_TypeCheck(ob, tp) \