Index: binaries/data/mods/public/maps/random/rmgen/placer/centered/DiskPlacer.js
===================================================================
--- binaries/data/mods/public/maps/random/rmgen/placer/centered/DiskPlacer.js
+++ binaries/data/mods/public/maps/random/rmgen/placer/centered/DiskPlacer.js
@@ -4,6 +4,7 @@
 function DiskPlacer(radius, centerPosition = undefined)
 {
 	this.radiusSquared = Math.square(radius);
+	this.radius = radius;
 	this.centerPosition = undefined;
 
 	if (centerPosition)
@@ -19,12 +20,19 @@
 {
 	let points = [];
 
-	for (let x = 0; x < g_Map.getSize(); ++x)
-		for (let y = 0; y < g_Map.getSize(); ++y)
+	const xMin = this.centerPosition.x - this.radius;
+	const xMax = this.centerPosition.x + this.radius;
+	const yMin = this.centerPosition.y - this.radius;
+	const yMax = this.centerPosition.y + this.radius;
+
+	let point = new Vector2D();
+	for (let x = xMin; x <= xMax; ++x)
+		for (let y = yMin; y <= yMax; ++y)
 		{
-			let point = new Vector2D(x, y);
-			if (this.centerPosition.distanceToSquared(point) <= this.radiusSquared && constraint.allows(point))
-				points.push(point);
+			point.set(x, y);
+
+			if (g_Map.validTile(point) && this.centerPosition.distanceToSquared(point) <= this.radiusSquared && constraint.allows(point))
+				points.push(point.clone());
 		}
 
 	return points;