diff --git a/CHANGES.rst b/CHANGES.rst
index e6305b5..2c38226 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -14,8 +14,8 @@ New features:
 
 Bug fixes:
 
-- *add item here*
-
+- Switch to new TestCase using AT after PloneTestcase is now DX.
+  [pbauer]
 
 2.1.19 (2018-02-02)
 -------------------
diff --git a/Products/contentmigration/tests/layer.py b/Products/contentmigration/tests/layer.py
index f410e7c..6f5e3a7 100644
--- a/Products/contentmigration/tests/layer.py
+++ b/Products/contentmigration/tests/layer.py
@@ -1,4 +1,4 @@
-from plone.app.testing import bbb
+from plone.app.testing import bbb_at
 from plone.app import testing
 from plone.testing import z2
 from Products.GenericSetup import EXTENSION, profile_registry
@@ -13,9 +13,9 @@ def setupSampleTypeProfile():
         EXTENSION)
 
 
-class PloneTestCaseFixture(bbb.PloneTestCaseFixture):
+class PloneTestCaseFixture(bbb_at.PloneTestCaseFixture):
 
-    defaultBases = (bbb.PTC_FIXTURE, )
+    defaultBases = (bbb_at.PTC_FIXTURE, )
 
     def setUpZope(self, app, configurationContext):
         setupSampleTypeProfile()