diff --git a/jsettlers.logic/src/main/java/jsettlers/logic/map/grid/MainGrid.java b/jsettlers.logic/src/main/java/jsettlers/logic/map/grid/MainGrid.java
index 9929f18d8..e8a6b185a 100644
--- a/jsettlers.logic/src/main/java/jsettlers/logic/map/grid/MainGrid.java
+++ b/jsettlers.logic/src/main/java/jsettlers/logic/map/grid/MainGrid.java
@@ -16,6 +16,7 @@
 
 import java.io.IOException;
 import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
 import java.io.Serializable;
 import java.util.BitSet;
 import java.util.Date;
@@ -141,7 +142,7 @@
  * @author Andreas Eberle
  */
 public final class MainGrid implements Serializable {
-	private static final long serialVersionUID = 3824511313693431423L;
+	private static final long serialVersionUID = 3824511313693431424L;
 
 	final String mapId;
 	final String mapName;
@@ -233,10 +234,20 @@ public void initForPlayer(byte playerId, FogOfWar fogOfWar) {
 
 	private void readObject(ObjectInputStream ois) throws IOException, ClassNotFoundException {
 		ois.defaultReadObject();
+
+		short width = ois.readShort();
+		short height = ois.readShort();
+
 		initAdditional();
 		this.bordersThread.checkArea(0, 0, width, height);
 	}
 
+	private void writeObject(ObjectOutputStream oos) throws IOException {
+		oos.defaultWriteObject();
+		oos.writeShort(width);
+		oos.writeShort(height);
+	}
+
 	public void startThreads() {
 		bordersThread.start();
 		if (fogOfWar != null) {
@@ -1220,7 +1231,7 @@ public boolean isInBounds(int x, int y) {
 	}
 
 	final class MovablePathfinderGrid extends AbstractMovableGrid {
-		private static final long serialVersionUID = 4006228724969442801L;
+		private static final long serialVersionUID = 4006228724969442802L;
 
 		private transient PathfinderGrid    pathfinderGrid;
 		private transient AbstractAStar     aStar;
@@ -1229,9 +1240,19 @@ final class MovablePathfinderGrid extends AbstractMovableGrid {
 
 		private void readObject(ObjectInputStream ois) throws IOException, ClassNotFoundException {
 			ois.defaultReadObject();
+
+			short width = ois.readShort();
+			short height = ois.readShort();
+
 			initPathfinders(width, height);
 		}
 
+		private void writeObject(ObjectOutputStream oos) throws IOException {
+			oos.defaultWriteObject();
+			oos.writeShort(width);
+			oos.writeShort(height);
+		}
+
 		public MovablePathfinderGrid() {
 			initPathfinders(width, height);
 		}