diff --git a/src/video_display.cpp b/src/video_display.cpp
index 8d85311a6..1919fc577 100644
--- a/src/video_display.cpp
+++ b/src/video_display.cpp
@@ -227,19 +227,19 @@ catch (const agi::Exception &err) {
 }
 
 void VideoDisplay::DrawOverscanMask(float horizontal_percent, float vertical_percent) const {
-	Vector2D v(viewport_width, viewport_height);
+	Vector2D v = Vector2D(viewport_width, viewport_height) / scale_factor;
 	Vector2D size = Vector2D(horizontal_percent, vertical_percent) / 2 * v;
 
 	// Clockwise from top-left
 	Vector2D corners[] = {
 		size,
-		Vector2D(viewport_width - size.X(), size),
+		Vector2D(viewport_width / scale_factor - size.X(), size),
 		v - size,
-		Vector2D(size, viewport_height - size.Y())
+		Vector2D(size, viewport_height  / scale_factor - size.Y())
 	};
 
 	// Shift to compensate for black bars
-	Vector2D pos(viewport_left, viewport_top);
+	Vector2D pos = Vector2D(viewport_left, viewport_top) / scale_factor;
 	for (auto& corner : corners)
 		corner = corner + pos;
 
@@ -261,7 +261,7 @@ void VideoDisplay::DrawOverscanMask(float horizontal_percent, float vertical_per
 
 	std::vector<int> vstart(1, 0);
 	std::vector<int> vcount(1, count);
-	gl.DrawMultiPolygon(points, vstart, vcount, Vector2D(viewport_left, viewport_top), Vector2D(viewport_width, viewport_height), true);
+	gl.DrawMultiPolygon(points, vstart, vcount, pos, v, true);
 }
 
 void VideoDisplay::PositionVideo() {