diff --git a/akka-docs/rst/project/migration-guide-2.2.x-2.3.x.rst b/akka-docs/rst/project/migration-guide-2.2.x-2.3.x.rst
index 4b5e2b6217..285fbf5748 100644
--- a/akka-docs/rst/project/migration-guide-2.2.x-2.3.x.rst
+++ b/akka-docs/rst/project/migration-guide-2.2.x-2.3.x.rst
@@ -248,3 +248,14 @@ Akka OSGi Aries Blueprint is Removed
 
 ``akka-osgi-aries`` has been removed. Similar can be implemented outside of Akka if needed.
  
+TestKit: reworked time dilation
+===============================
+
+``TestDuration`` has been changed into an implicit value class plus a Java API in JavaTestKit. Please change::
+
+    import akka.testkit.duration2TestDuration
+
+into::
+
+    import akka.testkit.TestDuration
+