Fixed #691
diff --git a/release-notes/CREDITS b/release-notes/CREDITS
index 655d66f..3226246 100644
--- a/release-notes/CREDITS
+++ b/release-notes/CREDITS
@@ -203,3 +203,7 @@
 Ludevik@github:
   * Reported #682: Class<?>-valued Map keys not serialized properly
    (2.5.1)
+
+Antibrumm@github:
+  * Reported #691: Jackson 2.5.0. NullSerializer for MapProperty failing
+   (2.5.2)