diff --git a/CHANGES.md b/CHANGES.md
index 4bf296d9a..6b89802ea 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -29,6 +29,7 @@ Changes from ns-3.39 to ns-3-dev
 * (lr-wpan) Added the possibility to obtain the LQI from a received `MlmeAssociateIndicationParams`.
 * (wifi) Added new helper methods to SpectrumWifiPhyHelper to allow flexible configuration for the mapping between spectrum PHY interfaces and PHY instances.
 * (wifi) Added new trace sources to `WifiPhy`: **OperatingChannelChange**, which is fired when the operating channel of a PHY is changed.
+* (wifi) The attribute `WifiPhy::Antennas` is extended to support up to 8 antennas.
 
 ### Changes to build system
 
diff --git a/RELEASE_NOTES.md b/RELEASE_NOTES.md
index c5afe3870..16a6be42d 100644
--- a/RELEASE_NOTES.md
+++ b/RELEASE_NOTES.md
@@ -36,6 +36,7 @@ requirements (Note: not all ns-3 features are available on all systems):
 - (lr-wpan) - !1645 - Add LQI to MlmeAssociateIndicationParams
 - (wifi) Added a new trace source to WifiPhy to indicate operating channel change
 - (wifi) Improved support for multiple spectrum PHY interfaces
+- (wifi) Added initial support for MU-MIMO (ideal PHY layer only)
 
 ### Bugs fixed