diff --git a/Lib/ctypes/test/test_strings.py b/Lib/ctypes/test/test_strings.py
index e28e141..5434efd 100644
--- a/Lib/ctypes/test/test_strings.py
+++ b/Lib/ctypes/test/test_strings.py
@@ -54,6 +54,13 @@
 ##        print BUF.from_param(c_char_p("python"))
 ##        print BUF.from_param(BUF(*"pyth"))
 
+    def test_del_segfault(self):
+        BUF = c_char * 4
+        buf = BUF()
+        with self.assertRaises(AttributeError):
+            del buf.raw
+
+
 @need_symbol('c_wchar')
 class WStringArrayTestCase(unittest.TestCase):
     def test(self):
diff --git a/Lib/sqlite3/test/regression.py b/Lib/sqlite3/test/regression.py
index 1c59a3c..865bd88 100644
--- a/Lib/sqlite3/test/regression.py
+++ b/Lib/sqlite3/test/regression.py
@@ -379,6 +379,10 @@
         del ref
         support.gc_collect()
 
+    def CheckDelIsolation_levelSegfault(self):
+        with self.assertRaises(AttributeError):
+            del self.con.isolation_level
+
 
 class UnhashableFunc:
     __hash__ = None
diff --git a/Lib/test/multibytecodec_support.py b/Lib/test/multibytecodec_support.py
index 813b7aa..cca8af6 100644
--- a/Lib/test/multibytecodec_support.py
+++ b/Lib/test/multibytecodec_support.py
@@ -277,6 +277,11 @@
         writer = self.writer(stream)
         writer.reset()
 
+    def test_incrementalencoder_del_segfault(self):
+        e = self.incrementalencoder()
+        with self.assertRaises(AttributeError):
+            del e.errors
+
 
 class TestBase_Mapping(unittest.TestCase):
     pass_enctest = []
diff --git a/Lib/test/test_asyncio/test_futures.py b/Lib/test/test_asyncio/test_futures.py
index 3339356..2e4583d 100644
--- a/Lib/test/test_asyncio/test_futures.py
+++ b/Lib/test/test_asyncio/test_futures.py
@@ -570,6 +570,13 @@
     except AttributeError:
         cls = None
 
+    def test_future_del_segfault(self):
+        fut = self._new_future(loop=self.loop)
+        with self.assertRaises(AttributeError):
+            del fut._asyncio_future_blocking
+        with self.assertRaises(AttributeError):
+            del fut._log_traceback
+
 
 @unittest.skipUnless(hasattr(futures, '_CFuture'),
                      'requires the C _asyncio module')
diff --git a/Lib/test/test_asyncio/test_tasks.py b/Lib/test/test_asyncio/test_tasks.py
index c65d1f2..22f14f8 100644
--- a/Lib/test/test_asyncio/test_tasks.py
+++ b/Lib/test/test_asyncio/test_tasks.py
@@ -2546,6 +2546,15 @@
             self.loop.run_until_complete(task)
         self.assertAlmostEqual(gettotalrefcount() - refs_before, 0, delta=10)
 
+    def test_del__log_destroy_pending_segfault(self):
+        @asyncio.coroutine
+        def coro():
+            pass
+        task = self.new_task(self.loop, coro())
+        self.loop.run_until_complete(task)
+        with self.assertRaises(AttributeError):
+            del task._log_destroy_pending
+
 
 @unittest.skipUnless(hasattr(futures, '_CFuture') and
                      hasattr(tasks, '_CTask'),
diff --git a/Lib/test/test_frame.py b/Lib/test/test_frame.py
index fd79508..d6aa283 100644
--- a/Lib/test/test_frame.py
+++ b/Lib/test/test_frame.py
@@ -109,10 +109,7 @@
             self.assertIs(None, wr())
 
 
-class FrameLocalsTest(unittest.TestCase):
-    """
-    Tests for the .f_locals attribute.
-    """
+class FrameAttrsTest(unittest.TestCase):
 
     def make_frames(self):
         def outer():
@@ -159,6 +156,11 @@
         self.assertEqual(outer.f_locals, {})
         self.assertEqual(inner.f_locals, {})
 
+    def test_f_lineno_del_segfault(self):
+        f, _, _ = self.make_frames()
+        with self.assertRaises(AttributeError):
+            del f.f_lineno
+
 
 class ReprTest(unittest.TestCase):
     """
diff --git a/Lib/test/test_io.py b/Lib/test/test_io.py
index 14352ff..dc353c1 100644
--- a/Lib/test/test_io.py
+++ b/Lib/test/test_io.py
@@ -3663,6 +3663,11 @@
             t2.buddy = t1
         support.gc_collect()
 
+    def test_del__CHUNK_SIZE_SystemError(self):
+        t = self.TextIOWrapper(self.BytesIO(), encoding='ascii')
+        with self.assertRaises(AttributeError):
+            del t._CHUNK_SIZE
+
 
 class PyTextIOWrapperTest(TextIOWrapperTest):
     io = pyio
diff --git a/Misc/NEWS.d/next/Core and Builtins/2018-12-15-14-01-45.bpo-35504.JtKczP.rst b/Misc/NEWS.d/next/Core and Builtins/2018-12-15-14-01-45.bpo-35504.JtKczP.rst
new file mode 100644
index 0000000..2a4f0f6
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2018-12-15-14-01-45.bpo-35504.JtKczP.rst
@@ -0,0 +1,2 @@
+Fix segfaults and :exc:`SystemError`\ s when deleting certain attributes.
+Patch by Zackery Spytz.
diff --git a/Modules/_asynciomodule.c b/Modules/_asynciomodule.c
index 0998cc1..7637cb7 100644
--- a/Modules/_asynciomodule.c
+++ b/Modules/_asynciomodule.c
@@ -1113,6 +1113,10 @@
     if (future_ensure_alive(fut)) {
         return -1;
     }
+    if (val == NULL) {
+        PyErr_SetString(PyExc_AttributeError, "cannot delete attribute");
+        return -1;
+    }
 
     int is_true = PyObject_IsTrue(val);
     if (is_true < 0) {
@@ -1137,6 +1141,10 @@
 static int
 FutureObj_set_log_traceback(FutureObj *fut, PyObject *val, void *Py_UNUSED(ignored))
 {
+    if (val == NULL) {
+        PyErr_SetString(PyExc_AttributeError, "cannot delete attribute");
+        return -1;
+    }
     int is_true = PyObject_IsTrue(val);
     if (is_true < 0) {
         return -1;
@@ -2015,6 +2023,10 @@
 static int
 TaskObj_set_log_destroy_pending(TaskObj *task, PyObject *val, void *Py_UNUSED(ignored))
 {
+    if (val == NULL) {
+        PyErr_SetString(PyExc_AttributeError, "cannot delete attribute");
+        return -1;
+    }
     int is_true = PyObject_IsTrue(val);
     if (is_true < 0) {
         return -1;
diff --git a/Modules/_ctypes/_ctypes.c b/Modules/_ctypes/_ctypes.c
index 163b3e3..637be42 100644
--- a/Modules/_ctypes/_ctypes.c
+++ b/Modules/_ctypes/_ctypes.c
@@ -1191,6 +1191,10 @@
     Py_ssize_t size;
     Py_buffer view;
 
+    if (value == NULL) {
+        PyErr_SetString(PyExc_AttributeError, "cannot delete attribute");
+        return -1;
+    }
     if (PyObject_GetBuffer(value, &view, PyBUF_SIMPLE) < 0)
         return -1;
     size = view.len;
diff --git a/Modules/_io/textio.c b/Modules/_io/textio.c
index 645d712..14f9488 100644
--- a/Modules/_io/textio.c
+++ b/Modules/_io/textio.c
@@ -3042,6 +3042,10 @@
 {
     Py_ssize_t n;
     CHECK_ATTACHED_INT(self);
+    if (arg == NULL) {
+        PyErr_SetString(PyExc_AttributeError, "cannot delete attribute");
+        return -1;
+    }
     n = PyNumber_AsSsize_t(arg, PyExc_ValueError);
     if (n == -1 && PyErr_Occurred())
         return -1;
diff --git a/Modules/_sqlite/connection.c b/Modules/_sqlite/connection.c
index aab4b1a..e3340bf 100644
--- a/Modules/_sqlite/connection.c
+++ b/Modules/_sqlite/connection.c
@@ -1161,6 +1161,10 @@
 static int
 pysqlite_connection_set_isolation_level(pysqlite_Connection* self, PyObject* isolation_level, void *Py_UNUSED(ignored))
 {
+    if (isolation_level == NULL) {
+        PyErr_SetString(PyExc_AttributeError, "cannot delete attribute");
+        return -1;
+    }
     if (isolation_level == Py_None) {
         PyObject *res = pysqlite_connection_commit(self, NULL);
         if (!res) {
diff --git a/Modules/_ssl.c b/Modules/_ssl.c
index 269f003..4e3352d 100644
--- a/Modules/_ssl.c
+++ b/Modules/_ssl.c
@@ -3625,6 +3625,10 @@
 set_post_handshake_auth(PySSLContext *self, PyObject *arg, void *c) {
     int (*verify_cb)(int, X509_STORE_CTX *) = NULL;
     int mode = SSL_CTX_get_verify_mode(self->ctx);
+    if (arg == NULL) {
+        PyErr_SetString(PyExc_AttributeError, "cannot delete attribute");
+        return -1;
+    }
     int pha = PyObject_IsTrue(arg);
 
     if (pha == -1) {
diff --git a/Modules/cjkcodecs/multibytecodec.c b/Modules/cjkcodecs/multibytecodec.c
index 938a774..f266e5f 100644
--- a/Modules/cjkcodecs/multibytecodec.c
+++ b/Modules/cjkcodecs/multibytecodec.c
@@ -133,6 +133,10 @@
     PyObject *cb;
     const char *str;
 
+    if (value == NULL) {
+        PyErr_SetString(PyExc_AttributeError, "cannot delete attribute");
+        return -1;
+    }
     if (!PyUnicode_Check(value)) {
         PyErr_SetString(PyExc_TypeError, "errors must be a string");
         return -1;
diff --git a/Objects/frameobject.c b/Objects/frameobject.c
index 400f99f..8488b96 100644
--- a/Objects/frameobject.c
+++ b/Objects/frameobject.c
@@ -105,6 +105,10 @@
     int blockstack[CO_MAXBLOCKS];       /* Walking the 'finally' blocks */
     int blockstack_top = 0;             /* (ditto) */
 
+    if (p_new_lineno == NULL) {
+        PyErr_SetString(PyExc_AttributeError, "cannot delete attribute");
+        return -1;
+    }
     /* f_lineno must be an integer. */
     if (!PyLong_CheckExact(p_new_lineno)) {
         PyErr_SetString(PyExc_ValueError,