diff --git a/RELEASE_NOTES.md b/RELEASE_NOTES.md
index b7163f51..4ce45384 100644
--- a/RELEASE_NOTES.md
+++ b/RELEASE_NOTES.md
@@ -1,3 +1,6 @@
+### 5.3.9
+- [e57] add default values to non-uniform data3d layouts (intensities, colors, classifications)
+
 ### 5.3.8
 - [e57] support for ScaledInteger with 33 to 63 bits (1 to 32, and 64 was already supported)