diff --git a/Doc/c-api/typeobj.rst b/Doc/c-api/typeobj.rst
index aa66784..e2f8f54 100644
--- a/Doc/c-api/typeobj.rst
+++ b/Doc/c-api/typeobj.rst
@@ -1099,6 +1099,11 @@
 
       .. versionadded:: 3.4
 
+      .. deprecated:: 3.8
+         This flag isn't necessary anymore, as the interpreter assumes the
+         :c:member:`~PyTypeObject.tp_finalize` slot is always present in the
+         type structure.
+
 
 .. c:member:: const char* PyTypeObject.tp_doc
 
diff --git a/Doc/whatsnew/3.8.rst b/Doc/whatsnew/3.8.rst
index b4a8030..5cd9a8e 100644
--- a/Doc/whatsnew/3.8.rst
+++ b/Doc/whatsnew/3.8.rst
@@ -1265,6 +1265,15 @@
 
   (Contributed by Zackery Spytz in :issue:`33407`.)
 
+* The interpreter does not pretend to support binary compatibility of
+  extension types accross feature releases, anymore.  A :c:type:`PyTypeObject`
+  exported by a third-party extension module is supposed to have all the
+  slots expected in the current Python version, including
+  :c:member:`~PyTypeObject.tp_finalize` (:const:`Py_TPFLAGS_HAVE_FINALIZE`
+  is not checked anymore before reading :c:member:`~PyTypeObject.tp_finalize`).
+
+  (Contributed by Antoine Pitrou in :issue:`32388`.)
+
 
 CPython bytecode changes
 ------------------------
diff --git a/Include/object.h b/Include/object.h
index 11ba2bb..cc98d8a 100644
--- a/Include/object.h
+++ b/Include/object.h
@@ -263,17 +263,14 @@
 #define Py_PRINT_RAW    1       /* No string quotes etc. */
 
 /*
-`Type flags (tp_flags)
+Type flags (tp_flags)
 
-These flags are used to extend the type structure in a backwards-compatible
-fashion. Extensions can use the flags to indicate (and test) when a given
-type structure contains a new feature. The Python core will use these when
-introducing new functionality between major revisions (to avoid mid-version
-changes in the PYTHON_API_VERSION).
+These flags are used to change expected features and behavior for a
+particular type.
 
 Arbitration of the flag bit positions will need to be coordinated among
 all extension writers who publicly release their extensions (this will
-be fewer than you might expect!)..
+be fewer than you might expect!).
 
 Most flags were removed as of Python 3.0 to make room for new flags.  (Some
 flags are not for backwards compatibility but to indicate the presence of an
@@ -302,7 +299,7 @@
 /* Set while the type is being 'readied', to prevent recursive ready calls */
 #define Py_TPFLAGS_READYING (1UL << 13)
 
-/* Objects support garbage collection (see objimp.h) */
+/* Objects support garbage collection (see objimpl.h) */
 #define Py_TPFLAGS_HAVE_GC (1UL << 14)
 
 /* These two bits are preserved for Stackless Python, next after this is 17 */
@@ -340,6 +337,11 @@
 /* NOTE: The following flags reuse lower bits (removed as part of the
  * Python 3.0 transition). */
 
+/* The following flag is kept for compatibility.  Starting with 3.8,
+ * binary compatibility of C extensions accross feature releases of
+ * Python is not supported anymore, except when using the stable ABI.
+ */
+
 /* Type structure has tp_finalize member (3.4) */
 #define Py_TPFLAGS_HAVE_FINALIZE (1UL << 0)
 
diff --git a/Misc/NEWS.d/next/Core and Builtins/2017-12-21-20-37-40.bpo-32388.6w-i5t.rst b/Misc/NEWS.d/next/Core and Builtins/2017-12-21-20-37-40.bpo-32388.6w-i5t.rst
new file mode 100644
index 0000000..60615d4
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2017-12-21-20-37-40.bpo-32388.6w-i5t.rst
@@ -0,0 +1 @@
+Remove cross-version binary compatibility requirement in tp_flags.
diff --git a/Modules/_asynciomodule.c b/Modules/_asynciomodule.c
index 6013608..d8b631b 100644
--- a/Modules/_asynciomodule.c
+++ b/Modules/_asynciomodule.c
@@ -1430,8 +1430,7 @@
     .tp_dealloc = FutureObj_dealloc,
     .tp_as_async = &FutureType_as_async,
     .tp_repr = (reprfunc)FutureObj_repr,
-    .tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_BASETYPE
-        | Py_TPFLAGS_HAVE_FINALIZE,
+    .tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_BASETYPE,
     .tp_doc = _asyncio_Future___init____doc__,
     .tp_traverse = (traverseproc)FutureObj_traverse,
     .tp_clear = (inquiry)FutureObj_clear,
@@ -2461,8 +2460,7 @@
     .tp_dealloc = TaskObj_dealloc,
     .tp_as_async = &FutureType_as_async,
     .tp_repr = (reprfunc)FutureObj_repr,
-    .tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_BASETYPE
-        | Py_TPFLAGS_HAVE_FINALIZE,
+    .tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_BASETYPE,
     .tp_doc = _asyncio_Task___init____doc__,
     .tp_traverse = (traverseproc)TaskObj_traverse,
     .tp_clear = (inquiry)TaskObj_clear,
diff --git a/Modules/_io/bufferedio.c b/Modules/_io/bufferedio.c
index 6f855b9..9c0eeb5 100644
--- a/Modules/_io/bufferedio.c
+++ b/Modules/_io/bufferedio.c
@@ -2342,8 +2342,7 @@
     0,                          /*tp_getattro*/
     0,                          /*tp_setattro*/
     0,                          /*tp_as_buffer*/
-    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE
-        | Py_TPFLAGS_HAVE_FINALIZE,  /*tp_flags*/
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,  /*tp_flags*/
     bufferediobase_doc,         /* tp_doc */
     0,                          /* tp_traverse */
     0,                          /* tp_clear */
@@ -2434,7 +2433,7 @@
     0,                          /*tp_setattro*/
     0,                          /*tp_as_buffer*/
     Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE
-        | Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_HAVE_FINALIZE, /*tp_flags*/
+        | Py_TPFLAGS_HAVE_GC,   /*tp_flags*/
     _io_BufferedReader___init____doc__, /* tp_doc */
     (traverseproc)buffered_traverse, /* tp_traverse */
     (inquiry)buffered_clear,    /* tp_clear */
@@ -2520,7 +2519,7 @@
     0,                          /*tp_setattro*/
     0,                          /*tp_as_buffer*/
     Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE
-        | Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_HAVE_FINALIZE,   /*tp_flags*/
+        | Py_TPFLAGS_HAVE_GC,   /*tp_flags*/
     _io_BufferedWriter___init____doc__, /* tp_doc */
     (traverseproc)buffered_traverse, /* tp_traverse */
     (inquiry)buffered_clear,    /* tp_clear */
@@ -2597,7 +2596,7 @@
     0,                          /*tp_setattro*/
     0,                          /*tp_as_buffer*/
     Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE
-        | Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_HAVE_FINALIZE,   /* tp_flags */
+        | Py_TPFLAGS_HAVE_GC,   /* tp_flags */
     _io_BufferedRWPair___init____doc__, /* tp_doc */
     (traverseproc)bufferedrwpair_traverse, /* tp_traverse */
     (inquiry)bufferedrwpair_clear, /* tp_clear */
@@ -2691,7 +2690,7 @@
     0,                          /*tp_setattro*/
     0,                          /*tp_as_buffer*/
     Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE
-        | Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_HAVE_FINALIZE,   /*tp_flags*/
+        | Py_TPFLAGS_HAVE_GC,   /*tp_flags*/
     _io_BufferedRandom___init____doc__, /* tp_doc */
     (traverseproc)buffered_traverse, /* tp_traverse */
     (inquiry)buffered_clear,    /* tp_clear */
diff --git a/Modules/_io/fileio.c b/Modules/_io/fileio.c
index 52a6f49..582a813 100644
--- a/Modules/_io/fileio.c
+++ b/Modules/_io/fileio.c
@@ -1200,12 +1200,12 @@
     0,                                          /* tp_setattro */
     0,                                          /* tp_as_buffer */
     Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE
-        | Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_HAVE_FINALIZE,       /* tp_flags */
+        | Py_TPFLAGS_HAVE_GC,                   /* tp_flags */
     _io_FileIO___init____doc__,                 /* tp_doc */
     (traverseproc)fileio_traverse,              /* tp_traverse */
     (inquiry)fileio_clear,                      /* tp_clear */
     0,                                          /* tp_richcompare */
-    offsetof(fileio, weakreflist),      /* tp_weaklistoffset */
+    offsetof(fileio, weakreflist),              /* tp_weaklistoffset */
     0,                                          /* tp_iter */
     0,                                          /* tp_iternext */
     fileio_methods,                             /* tp_methods */
@@ -1215,7 +1215,7 @@
     0,                                          /* tp_dict */
     0,                                          /* tp_descr_get */
     0,                                          /* tp_descr_set */
-    offsetof(fileio, dict),         /* tp_dictoffset */
+    offsetof(fileio, dict),                     /* tp_dictoffset */
     _io_FileIO___init__,                        /* tp_init */
     PyType_GenericAlloc,                        /* tp_alloc */
     fileio_new,                                 /* tp_new */
diff --git a/Modules/_io/iobase.c b/Modules/_io/iobase.c
index a5727b8..8c8112d 100644
--- a/Modules/_io/iobase.c
+++ b/Modules/_io/iobase.c
@@ -856,7 +856,7 @@
     0,                          /*tp_setattro*/
     0,                          /*tp_as_buffer*/
     Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE
-        | Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_HAVE_FINALIZE,   /*tp_flags*/
+        | Py_TPFLAGS_HAVE_GC,   /*tp_flags*/
     iobase_doc,                 /* tp_doc */
     (traverseproc)iobase_traverse, /* tp_traverse */
     (inquiry)iobase_clear,      /* tp_clear */
@@ -1051,7 +1051,7 @@
     0,                          /*tp_getattro*/
     0,                          /*tp_setattro*/
     0,                          /*tp_as_buffer*/
-    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HAVE_FINALIZE,  /*tp_flags*/
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,  /*tp_flags*/
     rawiobase_doc,              /* tp_doc */
     0,                          /* tp_traverse */
     0,                          /* tp_clear */
diff --git a/Modules/_io/textio.c b/Modules/_io/textio.c
index a08ab5b..3eb0dcc 100644
--- a/Modules/_io/textio.c
+++ b/Modules/_io/textio.c
@@ -183,8 +183,7 @@
     0,                          /*tp_getattro*/
     0,                          /*tp_setattro*/
     0,                          /*tp_as_buffer*/
-    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE
-        | Py_TPFLAGS_HAVE_FINALIZE,  /*tp_flags*/
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,  /*tp_flags*/
     textiobase_doc,             /* tp_doc */
     0,                          /* tp_traverse */
     0,                          /* tp_clear */
@@ -3258,7 +3257,7 @@
     0,                          /*tp_setattro*/
     0,                          /*tp_as_buffer*/
     Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE
-        | Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_HAVE_FINALIZE, /*tp_flags*/
+        | Py_TPFLAGS_HAVE_GC,   /*tp_flags*/
     _io_TextIOWrapper___init____doc__, /* tp_doc */
     (traverseproc)textiowrapper_traverse, /* tp_traverse */
     (inquiry)textiowrapper_clear, /* tp_clear */
diff --git a/Modules/_io/winconsoleio.c b/Modules/_io/winconsoleio.c
index 70a723e..7700bd5 100644
--- a/Modules/_io/winconsoleio.c
+++ b/Modules/_io/winconsoleio.c
@@ -1133,7 +1133,7 @@
     0,                                          /* tp_setattro */
     0,                                          /* tp_as_buffer */
     Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE
-        | Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_HAVE_FINALIZE,       /* tp_flags */
+        | Py_TPFLAGS_HAVE_GC,                   /* tp_flags */
     _io__WindowsConsoleIO___init____doc__,      /* tp_doc */
     (traverseproc)winconsoleio_traverse,        /* tp_traverse */
     (inquiry)winconsoleio_clear,                /* tp_clear */
diff --git a/Modules/_testmultiphase.c b/Modules/_testmultiphase.c
index db5bb7d..4933abb 100644
--- a/Modules/_testmultiphase.c
+++ b/Modules/_testmultiphase.c
@@ -98,7 +98,7 @@
     "_testimportexec.Example",
     sizeof(ExampleObject),
     0,
-    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_HAVE_FINALIZE,
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,
     Example_Type_slots
 };
 
diff --git a/Modules/gcmodule.c b/Modules/gcmodule.c
index 3b15c7b..0cf00e8 100644
--- a/Modules/gcmodule.c
+++ b/Modules/gcmodule.c
@@ -858,7 +858,6 @@
         PyObject *op = FROM_GC(gc);
         gc_list_move(gc, &seen);
         if (!_PyGCHead_FINALIZED(gc) &&
-                PyType_HasFeature(Py_TYPE(op), Py_TPFLAGS_HAVE_FINALIZE) &&
                 (finalize = Py_TYPE(op)->tp_finalize) != NULL) {
             _PyGCHead_SET_FINALIZED(gc);
             Py_INCREF(op);
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index a3d979c..a25ff7a 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -13032,8 +13032,7 @@
     0,                                      /* tp_getattro */
     0,                                      /* tp_setattro */
     0,                                      /* tp_as_buffer */
-    Py_TPFLAGS_DEFAULT
-        | Py_TPFLAGS_HAVE_FINALIZE,         /* tp_flags */
+    Py_TPFLAGS_DEFAULT,                     /* tp_flags */
     0,                                      /* tp_doc */
     0,                                      /* tp_traverse */
     0,                                      /* tp_clear */
diff --git a/Modules/socketmodule.c b/Modules/socketmodule.c
index 74cdc0f..ca4d760 100644
--- a/Modules/socketmodule.c
+++ b/Modules/socketmodule.c
@@ -5286,8 +5286,7 @@
     PyObject_GenericGetAttr,                    /* tp_getattro */
     0,                                          /* tp_setattro */
     0,                                          /* tp_as_buffer */
-    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE
-        | Py_TPFLAGS_HAVE_FINALIZE,             /* tp_flags */
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,   /* tp_flags */
     sock_doc,                                   /* tp_doc */
     0,                                          /* tp_traverse */
     0,                                          /* tp_clear */
diff --git a/Modules/xxlimited.c b/Modules/xxlimited.c
index 190f993..ffc04e0 100644
--- a/Modules/xxlimited.c
+++ b/Modules/xxlimited.c
@@ -123,7 +123,7 @@
     "xxlimited.Xxo",
     sizeof(XxoObject),
     0,
-    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_HAVE_FINALIZE,
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,
     Xxo_Type_slots
 };
 
diff --git a/Objects/genobject.c b/Objects/genobject.c
index e2def38..0d0a02d 100644
--- a/Objects/genobject.c
+++ b/Objects/genobject.c
@@ -742,8 +742,7 @@
     PyObject_GenericGetAttr,                    /* tp_getattro */
     0,                                          /* tp_setattro */
     0,                                          /* tp_as_buffer */
-    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
-        Py_TPFLAGS_HAVE_FINALIZE,               /* tp_flags */
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,    /* tp_flags */
     0,                                          /* tp_doc */
     (traverseproc)gen_traverse,                 /* tp_traverse */
     0,                                          /* tp_clear */
@@ -997,8 +996,7 @@
     PyObject_GenericGetAttr,                    /* tp_getattro */
     0,                                          /* tp_setattro */
     0,                                          /* tp_as_buffer */
-    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
-        Py_TPFLAGS_HAVE_FINALIZE,               /* tp_flags */
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,    /* tp_flags */
     0,                                          /* tp_doc */
     (traverseproc)gen_traverse,                 /* tp_traverse */
     0,                                          /* tp_clear */
@@ -1394,8 +1392,7 @@
     PyObject_GenericGetAttr,                    /* tp_getattro */
     0,                                          /* tp_setattro */
     0,                                          /* tp_as_buffer */
-    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
-        Py_TPFLAGS_HAVE_FINALIZE,               /* tp_flags */
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,    /* tp_flags */
     0,                                          /* tp_doc */
     (traverseproc)async_gen_traverse,           /* tp_traverse */
     0,                                          /* tp_clear */
diff --git a/Objects/object.c b/Objects/object.c
index 87dba98..f9c75b7 100644
--- a/Objects/object.c
+++ b/Objects/object.c
@@ -298,10 +298,7 @@
 {
     PyTypeObject *tp = Py_TYPE(self);
 
-    /* The former could happen on heaptypes created from the C API, e.g.
-       PyType_FromSpec(). */
-    if (!PyType_HasFeature(tp, Py_TPFLAGS_HAVE_FINALIZE) ||
-        tp->tp_finalize == NULL)
+    if (tp->tp_finalize == NULL)
         return;
     /* tp_finalize should only be called once. */
     if (PyType_IS_GC(tp) && _PyGC_FINALIZED(self))
diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index c14cbad..071ff27 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -248,8 +248,8 @@
        Invariants:
 
        - Py_TPFLAGS_VALID_VERSION_TAG is never set if
-         Py_TPFLAGS_HAVE_VERSION_TAG is not set (e.g. on type
-         objects coming from non-recompiled extension modules)
+         Py_TPFLAGS_HAVE_VERSION_TAG is not set (in case of a
+         bizarre MRO, see type_mro_modified()).
 
        - before Py_TPFLAGS_VALID_VERSION_TAG can be set on a type,
          it must first be set on all super types.
@@ -2571,7 +2571,7 @@
 
     /* Initialize tp_flags */
     type->tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HEAPTYPE |
-        Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HAVE_FINALIZE;
+        Py_TPFLAGS_BASETYPE;
     if (base->tp_flags & Py_TPFLAGS_HAVE_GC)
         type->tp_flags |= Py_TPFLAGS_HAVE_GC;
 
@@ -5179,10 +5179,7 @@
         COPYSLOT(tp_init);
         COPYSLOT(tp_alloc);
         COPYSLOT(tp_is_gc);
-        if ((type->tp_flags & Py_TPFLAGS_HAVE_FINALIZE) &&
-            (base->tp_flags & Py_TPFLAGS_HAVE_FINALIZE)) {
-            COPYSLOT(tp_finalize);
-        }
+        COPYSLOT(tp_finalize);
         if ((type->tp_flags & Py_TPFLAGS_HAVE_GC) ==
             (base->tp_flags & Py_TPFLAGS_HAVE_GC)) {
             /* They agree about gc. */