diff --git a/src/thumbnaildownloader.cpp b/src/thumbnaildownloader.cpp
index c496a14..ce8f9f8 100644
--- a/src/thumbnaildownloader.cpp
+++ b/src/thumbnaildownloader.cpp
@@ -18,7 +18,7 @@ ThumbnailDownloader::~ThumbnailDownloader()
 {
 }
 
-void ThumbnailDownloader::addDownload(QString url, QModelIndex index)
+void ThumbnailDownloader::addDownload(QString url, ThumbnailId index)
 {
     m_urlPairList.append({index, url});
     if (!m_isDownloading)
@@ -35,18 +35,18 @@ void ThumbnailDownloader::startDownload()
     downloadOnePair(m_urlPairList.takeFirst());
 }
 
-void ThumbnailDownloader::downloadOnePair(QPair<QModelIndex, QString> urlPair)
+void ThumbnailDownloader::downloadOnePair(ThumbnailInfo thumbnailInfo)
 {
-    QNetworkRequest req(urlPair.second);
+    QNetworkRequest req(thumbnailInfo.second);
     auto reply = manager.get(req);
     connect(reply, &QNetworkReply::finished, this, [=](){
-        fileDownloaded(reply, urlPair);
+        fileDownloaded(reply, thumbnailInfo);
     });
 }
 
-void ThumbnailDownloader::fileDownloaded(QNetworkReply *pReply, QPair<QModelIndex, QString> urlPair)
+void ThumbnailDownloader::fileDownloaded(QNetworkReply *pReply, ThumbnailInfo thumbnailInfo)
 {
     auto downloadedData = pReply->readAll();
-    emit oneThumbnailDownloaded(urlPair.first, urlPair.second, downloadedData);
+    emit oneThumbnailDownloaded(thumbnailInfo.first, thumbnailInfo.second, downloadedData);
     pReply->deleteLater();
 }
diff --git a/src/thumbnaildownloader.h b/src/thumbnaildownloader.h
index cce710c..12a81fa 100644
--- a/src/thumbnaildownloader.h
+++ b/src/thumbnaildownloader.h
@@ -12,25 +12,29 @@ class ThumbnailDownloader : public QObject
 {
     Q_OBJECT
 
+public:
+    typedef QModelIndex ThumbnailId;
+    typedef QPair<ThumbnailId, QString> ThumbnailInfo;
+
 public:
     ThumbnailDownloader(QObject *parent = 0);
     ~ThumbnailDownloader();
 
-    void addDownload(QString url, QModelIndex index);
+    void addDownload(QString url, ThumbnailId index);
     void startDownload();
-    void downloadOnePair(QPair<QModelIndex, QString> urlPair);
+    void downloadOnePair(ThumbnailInfo thumbnailInfo);
     void clearQueue() { m_urlPairList.clear(); }
 
 signals:
-    void oneThumbnailDownloaded(QModelIndex, QString, QByteArray);
+    void oneThumbnailDownloaded(ThumbnailId, QString, QByteArray);
 
 private:
-    QQueue<QPair<QModelIndex, QString>> m_urlPairList;
+    QQueue<ThumbnailInfo> m_urlPairList;
     QNetworkAccessManager manager;
     bool m_isDownloading = false;
 
 private slots:
-    void fileDownloaded(QNetworkReply *pReply, QPair<QModelIndex, QString> urlPair);
+    void fileDownloaded(QNetworkReply *pReply, ThumbnailInfo thumbnailInfo);
 
 };