diff -r 4646b64139c9 Lib/test/test_subclassinit.py
--- a/Lib/test/test_subclassinit.py	Fri Oct 07 23:46:22 2016 +0300
+++ b/Lib/test/test_subclassinit.py	Sun Oct 09 09:29:43 2016 +0300
@@ -133,20 +133,32 @@ class Test(unittest.TestCase):
     def test_set_name_error(self):
         class Descriptor:
             def __set_name__(self, owner, name):
-                raise RuntimeError
+                1/0
 
-        with self.assertRaises(RuntimeError):
-            class A:
-                d = Descriptor()
+        with self.assertRaises(RuntimeError) as cm:
+            class NotGoingToWork:
+                attr = Descriptor()
+
+        exc = cm.exception
+        self.assertRegex(str(exc), r'\bNotGoingToWork\b')
+        self.assertRegex(str(exc), r'\battr\b')
+        self.assertRegex(str(exc), r'\bDescriptor\b')
+        self.assertIsInstance(exc.__context__, ZeroDivisionError)
 
     def test_set_name_wrong(self):
         class Descriptor:
             def __set_name__(self):
                 pass
 
-        with self.assertRaises(TypeError):
-            class A:
-                d = Descriptor()
+        with self.assertRaises(RuntimeError) as cm:
+            class NotGoingToWork:
+                attr = Descriptor()
+
+        exc = cm.exception
+        self.assertRegex(str(exc), r'\bNotGoingToWork\b')
+        self.assertRegex(str(exc), r'\battr\b')
+        self.assertRegex(str(exc), r'\bDescriptor\b')
+        self.assertIsInstance(exc.__context__, TypeError)
 
     def test_set_name_lookup(self):
         resolved = []
diff -r 4646b64139c9 Objects/typeobject.c
--- a/Objects/typeobject.c	Fri Oct 07 23:46:22 2016 +0300
+++ b/Objects/typeobject.c	Sun Oct 09 09:29:43 2016 +0300
@@ -7005,8 +7005,16 @@ set_names(PyTypeObject *type)
         if (set_name != NULL) {
             tmp = PyObject_CallFunctionObjArgs(set_name, type, key, NULL);
             Py_DECREF(set_name);
-            if (tmp == NULL)
+            if (tmp == NULL) {
+                PyObject *exc, *val, *tb;
+                PyErr_Fetch(&exc, &val, &tb);
+                PyErr_Format(PyExc_RuntimeError,
+                    "Error calling __set_name__ on '%.100s' instance %R "
+                    "in '%.100s'",
+                    value->ob_type->tp_name, key, type->tp_name);
+                _PyErr_ChainExceptions(exc, val, tb);
                 return -1;
+            }
             else
                 Py_DECREF(tmp);
         }