diff --git a/CHANGELOG.md b/CHANGELOG.md
index ecb95ee2e..91a8b270e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 ## (Unreleased)
 
+BACKWARDS INCOMPATIBILITIES:
+
+  * `ssh_username` is now required if using communicator ssh. [GH-4172]
+
 IMPROVEMENTS:
 
   * builder/cloudstack: Support reusing an already associated public IP [GH-4149]