diff --git a/src/map/ENC/rastertile.cpp b/src/map/ENC/rastertile.cpp
index f2ba630b..fc04d942 100644
--- a/src/map/ENC/rastertile.cpp
+++ b/src/map/ENC/rastertile.cpp
@@ -200,4 +200,6 @@ void RasterTile::render()
 	//painter.setPen(Qt::red);
 	//painter.setBrush(Qt::NoBrush);
 	//painter.drawRect(QRect(_rect.topLeft(), _pixmap.size()));
+
+	_valid = true;
 }
diff --git a/src/map/ENC/rastertile.h b/src/map/ENC/rastertile.h
index b99abf40..d47d9593 100644
--- a/src/map/ENC/rastertile.h
+++ b/src/map/ENC/rastertile.h
@@ -18,11 +18,12 @@ public:
 	  const QList<MapData::Poly*> &polygons, const QList<MapData::Point*> &points)
 	  : _proj(proj), _transform(transform), _zoom(zoom), _rect(rect),
 	  _ratio(ratio), _pixmap(rect.width() * ratio, rect.height() * ratio),
-	  _lines(lines), _polygons(polygons), _points(points) {}
+	  _lines(lines), _polygons(polygons), _points(points), _valid(false) {}
 
 	int zoom() const {return _zoom;}
 	QPoint xy() const {return _rect.topLeft();}
 	const QPixmap &pixmap() const {return _pixmap;}
+	bool isValid() const {return _valid;}
 
 	void render();
 
@@ -48,6 +49,7 @@ private:
 	QList<MapData::Line*> _lines;
 	QList<MapData::Poly*> _polygons;
 	QList<MapData::Point*> _points;
+	bool _valid;
 };
 
 }
diff --git a/src/map/encmap.cpp b/src/map/encmap.cpp
index 26d15431..6372f819 100644
--- a/src/map/encmap.cpp
+++ b/src/map/encmap.cpp
@@ -1,9 +1,7 @@
 #include <QPainter>
 #include <QPixmapCache>
-#include <QtConcurrent>
 #include "common/range.h"
 #include "common/wgs84.h"
-#include "ENC/rastertile.h"
 #include "rectd.h"
 #include "pcs.h"
 #include "encmap.h"
@@ -58,6 +56,8 @@ int ENCMap::zoomFit(const QSize &size, const RectC &rect)
 
 int ENCMap::zoomIn()
 {
+	cancelJobs();
+
 	_zoom = qMin(_zoom + 1, ZOOMS.max());
 	updateTransform();
 	return _zoom;
@@ -65,6 +65,8 @@ int ENCMap::zoomIn()
 
 int ENCMap::zoomOut()
 {
+	cancelJobs();
+
 	_zoom = qMax(_zoom - 1, ZOOMS.min());
 	updateTransform();
 	return _zoom;
@@ -96,6 +98,55 @@ void ENCMap::updateTransform()
 	  _transform.proj2img(prect.bottomRight()));
 }
 
+bool ENCMap::isRunning(int zoom, const QPoint &xy) const
+{
+	for (int i = 0; i < _jobs.size(); i++) {
+		const QList<ENC::RasterTile> &tiles = _jobs.at(i)->tiles();
+		for (int j = 0; j < tiles.size(); j++) {
+			const ENC::RasterTile &mt = tiles.at(j);
+			if (mt.zoom() == zoom && mt.xy() == xy)
+				return true;
+		}
+	}
+
+	return false;
+}
+
+void ENCMap::runJob(ENCMapJob *job)
+{
+	_jobs.append(job);
+
+	connect(job, &ENCMapJob::finished, this, &ENCMap::jobFinished);
+	job->run();
+}
+
+void ENCMap::removeJob(ENCMapJob *job)
+{
+	_jobs.removeOne(job);
+	job->deleteLater();
+}
+
+void ENCMap::jobFinished(ENCMapJob *job)
+{
+	const QList<ENC::RasterTile> &tiles = job->tiles();
+
+	for (int i = 0; i < tiles.size(); i++) {
+		const ENC::RasterTile &mt = tiles.at(i);
+		if (mt.isValid())
+			QPixmapCache::insert(key(mt.zoom(), mt.xy()), mt.pixmap());
+	}
+
+	removeJob(job);
+
+	emit tilesLoaded();
+}
+
+void ENCMap::cancelJobs()
+{
+	for (int i = 0; i < _jobs.size(); i++)
+		_jobs.at(i)->cancel();
+}
+
 QString ENCMap::key(int zoom, const QPoint &xy) const
 {
 	return path() + "-" + QString::number(zoom) + "_"
@@ -116,6 +167,8 @@ void ENCMap::draw(QPainter *painter, const QRectF &rect, Flags flags)
 	for (int i = 0; i < width; i++) {
 		for (int j = 0; j < height; j++) {
 			QPoint ttl(tl.x() + i * TILE_SIZE, tl.y() + j * TILE_SIZE);
+			if (isRunning(_zoom, ttl))
+				continue;
 
 			QPixmap pm;
 			if (QPixmapCache::find(key(_zoom, ttl), &pm))
@@ -149,14 +202,19 @@ void ENCMap::draw(QPainter *painter, const QRectF &rect, Flags flags)
 		}
 	}
 
-	QFuture<void> future = QtConcurrent::map(tiles, &RasterTile::render);
-	future.waitForFinished();
+	if (!tiles.isEmpty()) {
+		if (flags & Map::Block) {
+			QFuture<void> future = QtConcurrent::map(tiles, &RasterTile::render);
+			future.waitForFinished();
 
-	for (int i = 0; i < tiles.size(); i++) {
-		const RasterTile &mt = tiles.at(i);
-		const QPixmap &pm = mt.pixmap();
-		painter->drawPixmap(mt.xy(), pm);
-		QPixmapCache::insert(key(mt.zoom(), mt.xy()), pm);
+			for (int i = 0; i < tiles.size(); i++) {
+				const RasterTile &mt = tiles.at(i);
+				const QPixmap &pm = mt.pixmap();
+				painter->drawPixmap(mt.xy(), pm);
+				QPixmapCache::insert(key(mt.zoom(), mt.xy()), pm);
+			}
+		} else
+			runJob(new ENCMapJob(tiles));
 	}
 }
 
diff --git a/src/map/encmap.h b/src/map/encmap.h
index adfc3703..3341477e 100644
--- a/src/map/encmap.h
+++ b/src/map/encmap.h
@@ -1,12 +1,42 @@
 #ifndef ENCMAP_H
 #define ENCMAP_H
 
+#include <QtConcurrent>
 #include "map.h"
 #include "projection.h"
 #include "transform.h"
 #include "ENC/mapdata.h"
+#include "ENC/rastertile.h"
 
-class QFile;
+class ENCMapJob : public QObject
+{
+	Q_OBJECT
+
+public:
+	ENCMapJob(const QList<ENC::RasterTile> &tiles)
+	  : _tiles(tiles) {}
+
+	void run()
+	{
+		connect(&_watcher, &QFutureWatcher<void>::finished, this,
+		  &ENCMapJob::handleFinished);
+		_future = QtConcurrent::map(_tiles, &ENC::RasterTile::render);
+		_watcher.setFuture(_future);
+	}
+	void cancel() {_future.cancel();}
+	const QList<ENC::RasterTile> &tiles() const {return _tiles;}
+
+signals:
+	void finished(ENCMapJob *job);
+
+private slots:
+	void handleFinished() {emit finished(this);}
+
+private:
+	QFutureWatcher<void> _watcher;
+	QFuture<void> _future;
+	QList<ENC::RasterTile> _tiles;
+};
 
 class ENCMap : public Map
 {
@@ -43,9 +73,16 @@ public:
 
 	static Map *create(const QString &path, const Projection &, bool *isMap);
 
+private slots:
+	void jobFinished(ENCMapJob *job);
+
 private:
 	Transform transform(int zoom) const;
 	void updateTransform();
+	bool isRunning(int zoom, const QPoint &xy) const;
+	void runJob(ENCMapJob *job);
+	void removeJob(ENCMapJob *job);
+	void cancelJobs();
 	QString key(int zoom, const QPoint &xy) const;
 
 	ENC::MapData _data;
@@ -56,6 +93,8 @@ private:
 	QRectF _bounds;
 	int _zoom;
 
+	QList<ENCMapJob*> _jobs;
+
 	bool _valid;
 	QString _errorString;
 };