diff --git a/openbr/gui/imageviewer.cpp b/openbr/gui/imageviewer.cpp
index 807aa37..ea2d6e9 100644
--- a/openbr/gui/imageviewer.cpp
+++ b/openbr/gui/imageviewer.cpp
@@ -78,6 +78,11 @@ void br::ImageViewer::updatePixmap(QImage image, bool async)
     }
 }
 
+QSize br::ImageViewer::sizeHint() const
+{
+    return QSize(width(), (src.height() * width() + /* round up */ src.width() - 1) / src.width());
+}
+
 /*** PROTECTED SLOTS ***/
 void br::ImageViewer::keyPressEvent(QKeyEvent *event)
 {
diff --git a/openbr/gui/imageviewer.h b/openbr/gui/imageviewer.h
index 072f33c..3e9612f 100644
--- a/openbr/gui/imageviewer.h
+++ b/openbr/gui/imageviewer.h
@@ -57,6 +57,7 @@ protected slots:
 
 private slots:
     void updatePixmap(QImage image, bool async = false);
+    QSize sizeHint() const;
 };
 
 } // namespace br