diff --git a/PVE/Storage/BTRFSPlugin.pm b/PVE/Storage/BTRFSPlugin.pm
index d3ab17c..09b38a2 100644
--- a/PVE/Storage/BTRFSPlugin.pm
+++ b/PVE/Storage/BTRFSPlugin.pm
@@ -67,6 +67,7 @@ sub options {
 	shared => { optional => 1 },
 	disable => { optional => 1 },
 	maxfiles => { optional => 1 },
+	'prune-backups'=> { optional => 1 },
 	content => { optional => 1 },
 	format => { optional => 1 },
 	is_mountpoint => { optional => 1 },