diff --git a/CHANGELOG.md b/CHANGELOG.md
index 65a5a0d..e1d5c5c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,7 +5,7 @@ In Development
 --------------
 
 * ownCloud updated to version 8.0.3.
-
+* Backups broke if the box's hostname was changed after installation.
 
 v0.09 (May 8, 2015)
 -------------------
diff --git a/management/backup.py b/management/backup.py
index 6b25ea7..1639126 100755
--- a/management/backup.py
+++ b/management/backup.py
@@ -180,8 +180,9 @@ def perform_backup(full_backup):
 	if len(passphrase) < 43: raise Exception("secret_key.txt's first line is too short!")
 	env_with_passphrase = { "PASSPHRASE" : passphrase }
 
-	# Update the backup mirror directory which mirrors the current
-	# STORAGE_ROOT (but excluding the backups themselves!).
+	# Run a backup of STORAGE_ROOT (but excluding the backups themselves!).
+	# --allow-source-mismatch is needed in case the box's hostname is changed
+	# after the first backup. See #396.
 	try:
 		shell('check_call', [
 			"/usr/bin/duplicity",