diff --git a/apis/device.go b/apis/device.go
index 238fbdb..21a24d4 100644
--- a/apis/device.go
+++ b/apis/device.go
@@ -276,7 +276,7 @@ func formatXML(data []byte) ([]byte, error) {
 
 func (d *Device) DumpHierarchy(compressed bool, pretty bool) (string, error) {
 	// 965 content = self.jsonrpc.dumpWindowHierarchy(compressed, None)
-	result, err := d.requestJsonRpc("dumpWindowHierarchy", compressed, nil)
+	result, err := d.requestJsonRpc("dumpWindowHierarchy", compressed)
 	if err != nil {
 		return "", err
 	}