diff --git a/runelite-client/src/main/java/net/runelite/client/rs/ClientLoader.java b/runelite-client/src/main/java/net/runelite/client/rs/ClientLoader.java
index 1dd110dc68..fb04be2ec2 100644
--- a/runelite-client/src/main/java/net/runelite/client/rs/ClientLoader.java
+++ b/runelite-client/src/main/java/net/runelite/client/rs/ClientLoader.java
@@ -50,6 +50,7 @@ import java.security.cert.CertificateException;
 import java.security.cert.CertificateFactory;
 import java.util.Arrays;
 import java.util.Collection;
+import java.util.Map;
 import java.util.function.Supplier;
 import java.util.jar.JarEntry;
 import java.util.jar.JarInputStream;
@@ -64,6 +65,7 @@ import static net.runelite.client.rs.ClientUpdateCheckMode.VANILLA;
 import net.runelite.client.ui.FatalErrorDialog;
 import net.runelite.client.ui.SplashScreen;
 import net.runelite.http.api.RuneLiteAPI;
+import net.runelite.http.api.worlds.World;
 import okhttp3.HttpUrl;
 import okhttp3.Request;
 import okhttp3.Response;
@@ -80,7 +82,7 @@ public class ClientLoader implements Supplier<Applet>
 	private ClientUpdateCheckMode updateCheckMode;
 	private Object client = null;
 
-	private HostSupplier hostSupplier = new HostSupplier();
+	private WorldSupplier worldSupplier = new WorldSupplier();
 	private RSConfig config;
 
 	public ClientLoader(ClientUpdateCheckMode updateCheckMode)
@@ -173,7 +175,7 @@ public class ClientLoader implements Supplier<Applet>
 			catch (IOException e)
 			{
 				log.info("Failed to get jav_config from host \"{}\" ({})", url.host(), e.getMessage());
-				String host = hostSupplier.get();
+				String host = worldSupplier.get().getAddress();
 				url = url.newBuilder().host(host).build();
 				err = e;
 			}
@@ -190,14 +192,19 @@ public class ClientLoader implements Supplier<Applet>
 				throw new IOException("Invalid or missing jav_config");
 			}
 
-			if (Strings.isNullOrEmpty(backupConfig.getRuneLiteGamepack()))
+			if (Strings.isNullOrEmpty(backupConfig.getRuneLiteGamepack()) || Strings.isNullOrEmpty(backupConfig.getRuneLiteWorldParam()))
 			{
 				throw new IOException("Backup config does not have RuneLite gamepack url");
 			}
 
 			// Randomize the codebase
-			String codebase = hostSupplier.get();
-			backupConfig.setCodebase("http://" + codebase + "/");
+			World world = worldSupplier.get();
+			backupConfig.setCodebase("http://" + world.getAddress() + "/");
+
+			// Update the world applet parameter
+			Map<String, String> appletProperties = backupConfig.getAppletProperties();
+			appletProperties.put(backupConfig.getRuneLiteWorldParam(), Integer.toString(world.getId()));
+
 			config = backupConfig;
 		}
 		catch (IOException ex)
@@ -347,7 +354,7 @@ public class ClientLoader implements Supplier<Applet>
 						throw e;
 					}
 
-					url = url.newBuilder().host(hostSupplier.get()).build();
+					url = url.newBuilder().host(worldSupplier.get().getAddress()).build();
 				}
 			}
 		}
diff --git a/runelite-client/src/main/java/net/runelite/client/rs/RSConfig.java b/runelite-client/src/main/java/net/runelite/client/rs/RSConfig.java
index a9841755b9..b1c43b14e9 100644
--- a/runelite-client/src/main/java/net/runelite/client/rs/RSConfig.java
+++ b/runelite-client/src/main/java/net/runelite/client/rs/RSConfig.java
@@ -59,4 +59,9 @@ class RSConfig
 	{
 		return classLoaderProperties.get("runelite.gamepack");
 	}
+
+	String getRuneLiteWorldParam()
+	{
+		return classLoaderProperties.get("runelite.worldparam");
+	}
 }
diff --git a/runelite-client/src/main/java/net/runelite/client/rs/HostSupplier.java b/runelite-client/src/main/java/net/runelite/client/rs/WorldSupplier.java
similarity index 79%
rename from runelite-client/src/main/java/net/runelite/client/rs/HostSupplier.java
rename to runelite-client/src/main/java/net/runelite/client/rs/WorldSupplier.java
index d9fb0f8509..6e143b1326 100644
--- a/runelite-client/src/main/java/net/runelite/client/rs/HostSupplier.java
+++ b/runelite-client/src/main/java/net/runelite/client/rs/WorldSupplier.java
@@ -40,43 +40,47 @@ import net.runelite.http.api.worlds.WorldClient;
 import net.runelite.http.api.worlds.WorldType;
 
 @Slf4j
-class HostSupplier implements Supplier<String>
+class WorldSupplier implements Supplier<World>
 {
 	private final Random random = new Random(System.nanoTime());
-	private Queue<String> hosts = new ArrayDeque<>();
+	private Queue<World> worlds = new ArrayDeque<>();
 
 	@Override
-	public String get()
+	public World get()
 	{
-		if (!hosts.isEmpty())
+		if (!worlds.isEmpty())
 		{
-			return hosts.poll();
+			return worlds.poll();
 		}
 
 		try
 		{
-			List<String> newHosts = new WorldClient(RuneLiteAPI.CLIENT)
+			List<World> newWorlds = new WorldClient(RuneLiteAPI.CLIENT)
 				.lookupWorlds()
 				.getWorlds()
 				.stream()
 				.filter(w -> w.getTypes().isEmpty() || EnumSet.of(WorldType.MEMBERS).equals(w.getTypes()))
-				.map(World::getAddress)
 				.collect(Collectors.toList());
 
-			Collections.shuffle(newHosts, random);
+			Collections.shuffle(newWorlds, random);
 
-			hosts.addAll(newHosts.subList(0, 16));
+			worlds.addAll(newWorlds.subList(0, 16));
 		}
 		catch (IOException e)
 		{
 			log.warn("Unable to retrieve world list", e);
 		}
 
-		while (hosts.size() < 2)
+		while (worlds.size() < 2)
 		{
-			hosts.add("oldschool" + (random.nextInt(50) + 1) + ".runescape.COM");
+			int id = random.nextInt(50) + 1;
+			World world = World.builder()
+				.id(300 + id) // worlds start at 300
+				.address("oldschool" + id + ".runescape.COM")
+				.build();
+			worlds.add(world);
 		}
 
-		return hosts.poll();
+		return worlds.poll();
 	}
 }