diff --git a/Misc/NEWS b/Misc/NEWS
index 1dc300d..3a15837 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -100,7 +100,8 @@
     map(), filter(), reduce(), zip()
     list(), tuple() (PySequence_Tuple() and PySequence_Fast() in C API)
     max(), min()
-    .join() method of strings
+    join() method of strings
+    extend() method of lists
     'x in y' and 'x not in y' (PySequence_Contains() in C API)
     operator.countOf() (PySequence_Count() in C API)
 
diff --git a/Objects/listobject.c b/Objects/listobject.c
index 9fb3e82..e595c85 100644
--- a/Objects/listobject.c
+++ b/Objects/listobject.c
@@ -644,7 +644,7 @@
 static PyObject *
 list_inplace_concat(PyListObject *self, PyObject *other)
 {
-	other = PySequence_Fast(other, "argument to += must be a sequence");
+	other = PySequence_Fast(other, "argument to += must be iterable");
 	if (!other)
 		return NULL;
 
@@ -664,7 +664,7 @@
 	if (!PyArg_ParseTuple(args, "O:extend", &b))
 		return NULL;
 
-	b = PySequence_Fast(b, "list.extend() argument must be a sequence");
+	b = PySequence_Fast(b, "list.extend() argument must be iterable");
 	if (!b)
 		return NULL;