diff --git a/scriptengine.cpp b/scriptengine.cpp
index 9e8bd3a..54defa0 100644
--- a/scriptengine.cpp
+++ b/scriptengine.cpp
@@ -12,8 +12,8 @@
 namespace Script
 {
 
-ScriptEngine::ScriptEngine(QDialog *parent) : QObject(parent)
-  , _jsEngine(new QJSEngine(this))
+ScriptEngine::ScriptEngine(QDialog *parent)
+  : _jsEngine(new QJSEngine(this))
   , _database(new Database(this))
   , _parent(parent)
   , _pool(new QThreadPool(this))
diff --git a/scriptengine.h b/scriptengine.h
index cd982fa..9c53108 100644
--- a/scriptengine.h
+++ b/scriptengine.h
@@ -104,8 +104,8 @@ public:
     Q_INVOKABLE bool isMarked() const;
     Q_INVOKABLE File* copy(const QString &newpath) const;
     Q_INVOKABLE bool move(const QString &newpath);
-    Q_INVOKABLE File* convert(const QString &outpath, const QString &format, const QVariantMap &params);
-    Q_INVOKABLE File* convertAsync(const QString &outpath, const QString &format, const QVariantMap &params);
+    Q_INVOKABLE File* convert(const QString &outpath, const QString &format, const QVariantMap &params = QVariantMap());
+    Q_INVOKABLE File* convertAsync(const QString &outpath, const QString &format, const QVariantMap &params = QVariantMap());
     Q_INVOKABLE QJSValue stats();
 };