diff --git a/Lib/test/test_capi/test_long.py b/Lib/test/test_capi/test_long.py
index 18507ed7c3bfec..05b3a7ebd63d64 100644
--- a/Lib/test/test_capi/test_long.py
+++ b/Lib/test/test_capi/test_long.py
@@ -208,9 +208,8 @@ def check_long_asintandoverflow(self, func, min_val, max_val):
 
         self.assertEqual(func(min_val - 1), (-1, -1))
         self.assertEqual(func(max_val + 1), (-1, +1))
-
-        # CRASHES func(1.0)
-        # CRASHES func(NULL)
+        self.assertRaises(SystemError, func, None)
+        self.assertRaises(TypeError, func, 1.0)
 
     def test_long_aslong(self):
         # Test PyLong_AsLong() and PyLong_FromLong()
diff --git a/Modules/_testcapi/long.c b/Modules/_testcapi/long.c
index 9c5a0e386759e7..16eb437ffea178 100644
--- a/Modules/_testcapi/long.c
+++ b/Modules/_testcapi/long.c
@@ -629,7 +629,7 @@ pylong_aslongandoverflow(PyObject *module, PyObject *arg)
     int overflow = UNINITIALIZED_INT;
     long value = PyLong_AsLongAndOverflow(arg, &overflow);
     if (value == -1 && PyErr_Occurred()) {
-        assert(overflow == -1);
+        assert(overflow == 0);
         return NULL;
     }
     return Py_BuildValue("li", value, overflow);
@@ -675,7 +675,7 @@ pylong_aslonglongandoverflow(PyObject *module, PyObject *arg)
     int overflow = UNINITIALIZED_INT;
     long long value = PyLong_AsLongLongAndOverflow(arg, &overflow);
     if (value == -1 && PyErr_Occurred()) {
-        assert(overflow == -1);
+        assert(overflow == 0);
         return NULL;
     }
     return Py_BuildValue("Li", value, overflow);