diff --git a/Objects/enumobject.c b/Objects/enumobject.c
index c458cfe..dae166d 100644
--- a/Objects/enumobject.c
+++ b/Objects/enumobject.c
@@ -250,6 +250,13 @@
         return NULL;
 
     reversed_meth = _PyObject_LookupSpecial(seq, &PyId___reversed__);
+    if (reversed_meth == Py_None) {
+        Py_DECREF(reversed_meth);
+        PyErr_Format(PyExc_TypeError,
+                     "'%.200s' object is not reversible",
+                     Py_TYPE(seq)->tp_name);
+        return NULL;
+    }
     if (reversed_meth != NULL) {
         PyObject *res = PyObject_CallFunctionObjArgs(reversed_meth, NULL);
         Py_DECREF(reversed_meth);
@@ -259,8 +266,9 @@
         return NULL;
 
     if (!PySequence_Check(seq)) {
-        PyErr_SetString(PyExc_TypeError,
-                        "argument to reversed() must be a sequence");
+        PyErr_Format(PyExc_TypeError,
+                     "'%.200s' object is not reversible",
+                     Py_TYPE(seq)->tp_name);
         return NULL;
     }
 
diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index b1686d2..1b4c261 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -5856,6 +5856,13 @@
     _Py_IDENTIFIER(__contains__);
 
     func = lookup_maybe(self, &PyId___contains__);
+    if (func == Py_None) {
+        Py_DECREF(func);
+        PyErr_Format(PyExc_TypeError,
+                     "'%.200s' object is not a container",
+                     Py_TYPE(self)->tp_name);
+        return -1;
+    }
     if (func != NULL) {
         args = PyTuple_Pack(1, value);
         if (args == NULL)
@@ -6241,6 +6248,13 @@
     _Py_IDENTIFIER(__iter__);
 
     func = lookup_method(self, &PyId___iter__);
+    if (func == Py_None) {
+        Py_DECREF(func);
+        PyErr_Format(PyExc_TypeError,
+                     "'%.200s' object is not iterable",
+                     Py_TYPE(self)->tp_name);
+        return NULL;
+    }
     if (func != NULL) {
         PyObject *args;
         args = res = PyTuple_New(0);