diff --git a/Lib/test/test_call.py b/Lib/test/test_call.py
index e4ab33c..9f0a75b 100644
--- a/Lib/test/test_call.py
+++ b/Lib/test/test_call.py
@@ -402,7 +402,7 @@
                     result = _testcapi.pyobject_fastcall(func, None)
                     self.check_result(result, expected)
 
-    def test_fastcall_dict(self):
+    def test_vectorcall_dict(self):
         # Test _PyObject_FastCallDict()
 
         for func, args, expected in self.CALLS_POSARGS:
@@ -429,33 +429,33 @@
                 result = _testcapi.pyobject_fastcalldict(func, args, kwargs)
                 self.check_result(result, expected)
 
-    def test_fastcall_keywords(self):
-        # Test _PyObject_FastCallKeywords()
+    def test_vectorcall(self):
+        # Test _PyObject_Vectorcall()
 
         for func, args, expected in self.CALLS_POSARGS:
             with self.subTest(func=func, args=args):
                 # kwnames=NULL
-                result = _testcapi.pyobject_fastcallkeywords(func, args, None)
+                result = _testcapi.pyobject_vectorcall(func, args, None)
                 self.check_result(result, expected)
 
                 # kwnames=()
-                result = _testcapi.pyobject_fastcallkeywords(func, args, ())
+                result = _testcapi.pyobject_vectorcall(func, args, ())
                 self.check_result(result, expected)
 
                 if not args:
                     # kwnames=NULL
-                    result = _testcapi.pyobject_fastcallkeywords(func, None, None)
+                    result = _testcapi.pyobject_vectorcall(func, None, None)
                     self.check_result(result, expected)
 
                     # kwnames=()
-                    result = _testcapi.pyobject_fastcallkeywords(func, None, ())
+                    result = _testcapi.pyobject_vectorcall(func, None, ())
                     self.check_result(result, expected)
 
         for func, args, kwargs, expected in self.CALLS_KWARGS:
             with self.subTest(func=func, args=args, kwargs=kwargs):
                 kwnames = tuple(kwargs.keys())
                 args = args + tuple(kwargs.values())
-                result = _testcapi.pyobject_fastcallkeywords(func, args, kwnames)
+                result = _testcapi.pyobject_vectorcall(func, args, kwnames)
                 self.check_result(result, expected)
 
     def test_fastcall_clearing_dict(self):
diff --git a/Lib/test/test_capi.py b/Lib/test/test_capi.py
index f3d41a2..0813abb 100644
--- a/Lib/test/test_capi.py
+++ b/Lib/test/test_capi.py
@@ -34,6 +34,11 @@
     """some doc"""
     return self
 
+def testfunction_kw(self, *, kw):
+    """some doc"""
+    return self
+
+
 class InstanceMethod:
     id = _testcapi.instancemethod(id)
     testfunction = _testcapi.instancemethod(testfunction)
@@ -479,6 +484,48 @@
             pass
         self.assertFalse(MethodDescriptorHeap.__flags__ & Py_TPFLAGS_METHOD_DESCRIPTOR)
 
+    def test_vectorcall(self):
+        # Test a bunch of different ways to call objects:
+        # 1. normal call
+        # 2. vectorcall using _PyObject_Vectorcall()
+        # 3. vectorcall using PyVectorcall_Call()
+        # 4. call as bound method
+        # 5. call using functools.partial
+
+        # A list of (function, args, kwargs, result) calls to test
+        calls = [(len, (range(42),), {}, 42),
+                 (list.append, ([], 0), {}, None),
+                 ([].append, (0,), {}, None),
+                 (sum, ([36],), {"start":6}, 42),
+                 (testfunction, (42,), {}, 42),
+                 (testfunction_kw, (42,), {"kw":None}, 42)]
+
+        from _testcapi import pyobject_vectorcall, pyvectorcall_call
+        from types import MethodType
+        from functools import partial
+
+        def vectorcall(func, args, kwargs):
+            args = *args, *kwargs.values()
+            kwnames = tuple(kwargs)
+            return pyobject_vectorcall(func, args, kwnames)
+
+        for (func, args, kwargs, expected) in calls:
+            with self.subTest(str(func)):
+                args1 = args[1:]
+                meth = MethodType(func, args[0])
+                wrapped = partial(func)
+                if not kwargs:
+                    self.assertEqual(expected, func(*args))
+                    self.assertEqual(expected, pyobject_vectorcall(func, args, None))
+                    self.assertEqual(expected, pyvectorcall_call(func, args))
+                    self.assertEqual(expected, meth(*args1))
+                    self.assertEqual(expected, wrapped(*args))
+                self.assertEqual(expected, func(*args, **kwargs))
+                self.assertEqual(expected, vectorcall(func, args, kwargs))
+                self.assertEqual(expected, pyvectorcall_call(func, args, kwargs))
+                self.assertEqual(expected, meth(*args1, **kwargs))
+                self.assertEqual(expected, wrapped(*args, **kwargs))
+
 
 class SubinterpreterTest(unittest.TestCase):
 
diff --git a/Lib/test/test_sys.py b/Lib/test/test_sys.py
index dfe63b1..c558d11 100644
--- a/Lib/test/test_sys.py
+++ b/Lib/test/test_sys.py
@@ -1064,7 +1064,7 @@
         # buffer
         # XXX
         # builtin_function_or_method
-        check(len, size('4P')) # XXX check layout
+        check(len, size('5P'))
         # bytearray
         samples = [b'', b'u'*100000]
         for sample in samples:
@@ -1095,7 +1095,7 @@
         # complex
         check(complex(0,1), size('2d'))
         # method_descriptor (descriptor object)
-        check(str.lower, size('3PP'))
+        check(str.lower, size('3PPP'))
         # classmethod_descriptor (descriptor object)
         # XXX
         # member_descriptor (descriptor object)
@@ -1164,7 +1164,7 @@
         check(x, vsize('5P2c4P3ic' + CO_MAXBLOCKS*'3i' + 'P' + extras*'P'))
         # function
         def func(): pass
-        check(func, size('12P'))
+        check(func, size('13P'))
         class c():
             @staticmethod
             def foo():
@@ -1259,7 +1259,7 @@
         check((1,2,3), vsize('') + 3*self.P)
         # type
         # static type: PyTypeObject
-        fmt = 'P2n15Pl4Pn9Pn11PIP'
+        fmt = 'P2nPI13Pl4Pn9Pn11PIPP'
         if hasattr(sys, 'getcounts'):
             fmt += '3n2P'
         s = vsize(fmt)