diff --git a/docs/ref/models/querysets.txt b/docs/ref/models/querysets.txt
index 74fd813215baa..252b59b181770 100644
--- a/docs/ref/models/querysets.txt
+++ b/docs/ref/models/querysets.txt
@@ -1421,9 +1421,10 @@ do not support ``nowait``, such as MySQL, will cause a
 unexpectedly blocking.
 
 Evaluating a queryset with ``select_for_update`` in autocommit mode is
-an error because the rows are then not locked. If allowed, this would
-facilitate data corruption, and could easily be caused by calling,
-outside of any transaction, code that expects to be run in one.
+a :exc:`~django.db.transaction.TransactionManagementError` error because the
+rows are then not locked. If allowed, this would facilitate data corruption, and
+could easily be caused by calling, outside of any transaction, code that expects
+to be run in one.
 
 Using ``select_for_update`` on backends which do not support
 ``SELECT ... FOR UPDATE`` (such as SQLite) will have no effect.
@@ -1433,6 +1434,17 @@ Using ``select_for_update`` on backends which do not support
     It is now an error to execute a query with ``select_for_update()`` in
     autocommit mode. With earlier releases in the 1.6 series it was a no-op.
 
+.. warning::
+
+  Although `select_for_update() normally fails in autocommit mode, since
+  :class:`~django.test.TestCase` automatically wraps each test in a transaction,
+  calling `select_for_update()` in a `TestCase` even without an
+  :func:`~django.db.transaction.atomic()` block will unexpectedly
+  pass without raising a `TransactionManagementError`. To properly test
+  `select_for_update()` you should use
+  :class:`~django.test.TransactionTestCase`.
+
+
 raw
 ~~~
 
diff --git a/docs/topics/testing/tools.txt b/docs/topics/testing/tools.txt
index ecff777263d58..9f671044a892b 100644
--- a/docs/topics/testing/tools.txt
+++ b/docs/topics/testing/tools.txt
@@ -636,7 +636,10 @@ to test the effects of commit and rollback:
     While ``commit`` and ``rollback`` operations still *appear* to work when
     used in ``TestCase``, no actual commit or rollback will be performed by the
     database. This can cause your tests to pass or fail unexpectedly. Always
-    use ``TransactionTestCase`` when testing transactional behavior.
+    use ``TransactionTestCase`` when testing transactional behavior or any code
+    that can't normally be excuted in autocommit mode
+    (:meth:`~django.db.models.query.QuerySet.select_for_update()` is an
+    example).
 
 ``TransactionTestCase`` inherits from :class:`~django.test.SimpleTestCase`.