diff --git a/changelog.d/6117.misc b/changelog.d/6117.misc
new file mode 100644
index 000000000..f8bdb58f4
--- /dev/null
+++ b/changelog.d/6117.misc
@@ -0,0 +1 @@
+Fix up sample config entry for `redaction_retention_period` option.
diff --git a/docs/sample_config.yaml b/docs/sample_config.yaml
index 254e1b17b..43893399a 100644
--- a/docs/sample_config.yaml
+++ b/docs/sample_config.yaml
@@ -314,7 +314,7 @@ listeners:
 #
 # Defaults to `7d`. Set to `null` to disable.
 #
-redaction_retention_period: 7d
+#redaction_retention_period: 28d
 
 # How long to track users' last seen time and IPs in the database.
 #
diff --git a/synapse/config/server.py b/synapse/config/server.py
index 5ad7ee911..536ee7f29 100644
--- a/synapse/config/server.py
+++ b/synapse/config/server.py
@@ -742,7 +742,7 @@ class ServerConfig(Config):
         #
         # Defaults to `7d`. Set to `null` to disable.
         #
-        redaction_retention_period: 7d
+        #redaction_retention_period: 28d
 
         # How long to track users' last seen time and IPs in the database.
         #