diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7b572a331..7815f6cf9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,17 +5,21 @@ DEPRECATIONS/CHANGES:
  * Token Auth Backend Roles parameter types: For `allowed_policies` and
    `disallowed_policies` in role definitions in the token auth backend, input
    can now be a comma-separated string or an array of strings. Reading a role
-   will now return arrays for these parameters. 
+   will now return arrays for these parameters.
 
 IMPROVEMENTS:
 
- * auth/token: `allowed_policies` and `disallowed_policies` can now be
-   specified as a comma-separated string or an array of strings
+ * auth/token: `allowed_policies` and `disallowed_policies` can now be specified
+   as a comma-separated string or an array of strings [GH-3641]
+ * database/mongodb: Add optional `write_concern` parameter, which can be set
+   during database configuration. This establishes a session-wide [write
+   concern](https://docs.mongodb.com/manual/reference/write-concern/) for the
+   lifecycle of the mount [GH-3646]
 
 BUG FIXES:
 
- * database/mysql: Allow the creation statement to use commands that are not
-   yet supported by the prepare statement protocol [GH-3619]
+ * database/mysql: Allow the creation statement to use commands that are not yet
+   supported by the prepare statement protocol [GH-3619]
  * core: Fix potential panic that could occur using plugins when a node
    transitioned from active to standby [GH-3638]