diff --git a/PVE/API2/Storage/PruneBackups.pm b/PVE/API2/Storage/PruneBackups.pm
index 2509a46..e6ab276 100644
--- a/PVE/API2/Storage/PruneBackups.pm
+++ b/PVE/API2/Storage/PruneBackups.pm
@@ -61,9 +61,10 @@ __PACKAGE__->register_method ({
 		    type => 'integer',
 		},
 		'mark' => {
-		    description => "Whether the backup would be kept or removed. For backups that don't " .
-				   "use the standard naming scheme, it's 'protected'.",
+		    description => "Whether the backup would be kept or removed. Backups that are" .
+			" protected or don't use the standard naming scheme are not removed.",
 		    type => 'string',
+		    enum => ['keep', 'remove', 'protected', 'renamed'],
 		},
 		type => {
 		    description => "One of 'qemu', 'lxc', 'openvz' or 'unknown'.",
diff --git a/PVE/Storage/Plugin.pm b/PVE/Storage/Plugin.pm
index 409a05c..7d2487f 100644
--- a/PVE/Storage/Plugin.pm
+++ b/PVE/Storage/Plugin.pm
@@ -1372,7 +1372,7 @@ sub prune_backups {
 	    push @{$backup_groups->{$group}}, $prune_entry;
 	} else {
 	    # ignore backups that don't use the standard naming scheme
-	    $prune_entry->{mark} = 'protected';
+	    $prune_entry->{mark} = 'renamed';
 	}
 
 	$prune_entry->{mark} = 'protected' if $backup->{protected};
diff --git a/test/prune_backups_test.pm b/test/prune_backups_test.pm
index 8ad6144..b57d280 100644
--- a/test/prune_backups_test.pm
+++ b/test/prune_backups_test.pm
@@ -189,7 +189,7 @@ sub generate_expected {
 		'volid' => "$storeid:backup/vzdump-$vmid-renamed.tar.zst",
 		'type'  => 'unknown',
 		'ctime' => 1234,
-		'mark'  => 'protected',
+		'mark'  => 'renamed',
 		'vmid'  => $vmid,
 	    },
 	) if !defined($type);
@@ -375,7 +375,7 @@ my $tests = [
 	    {
 		'volid' => "$storeid:backup/vzdump-lxc-novmid.tar.gz",
 		'ctime' => 1234,
-		'mark'  => 'protected',
+		'mark'  => 'renamed',
 		'type'  => 'lxc',
 	    },
 	],