diff --git a/src/client/HostLobbyModal.ts b/src/client/HostLobbyModal.ts
index 6436cc04d..53c1befcb 100644
--- a/src/client/HostLobbyModal.ts
+++ b/src/client/HostLobbyModal.ts
@@ -789,23 +789,20 @@ export class HostLobbyModal extends BaseModal {
             disabledUnits: this.disabledUnits,
             spawnImmunityDuration: this.spawnImmunity
               ? spawnImmunityTicks
-              : undefined,
+              : null,
             playerTeams: this.teamCount,
             nations: sliderToNationsConfig(
               this.nations,
               this.defaultNationCount,
             ),
-            maxTimerValue:
-              this.maxTimer === true ? this.maxTimerValue : undefined,
+            maxTimerValue: this.maxTimer === true ? this.maxTimerValue : null,
             goldMultiplier:
-              this.goldMultiplier === true
-                ? this.goldMultiplierValue
-                : undefined,
+              this.goldMultiplier === true ? this.goldMultiplierValue : null,
             startingGold:
               this.startingGold === true && this.startingGoldValue !== undefined
                 ? Math.round(this.startingGoldValue * 1_000_000)
-                : undefined,
-            disableAlliances: this.disableAlliances || undefined,
+                : null,
+            disableAlliances: this.disableAlliances || null,
           } satisfies Partial<GameConfig>,
         },
         bubbles: true,
diff --git a/src/client/graphics/layers/GameRightSidebar.ts b/src/client/graphics/layers/GameRightSidebar.ts
index 67f5ed1dc..0daf3f323 100644
--- a/src/client/graphics/layers/GameRightSidebar.ts
+++ b/src/client/graphics/layers/GameRightSidebar.ts
@@ -99,7 +99,10 @@ export class GameRightSidebar extends LitElement implements Layer {
     const elapsedSeconds = Math.floor(gameTicks / 10); // 10 ticks per second
 
     if (this.game.inSpawnPhase()) {
-      this.timer = maxTimerValue !== undefined ? maxTimerValue * 60 : 0;
+      this.timer =
+        maxTimerValue !== null && maxTimerValue !== undefined
+          ? maxTimerValue * 60
+          : 0;
       return;
     }
 
@@ -107,7 +110,7 @@ export class GameRightSidebar extends LitElement implements Layer {
       return;
     }
 
-    if (maxTimerValue !== undefined) {
+    if (maxTimerValue !== null && maxTimerValue !== undefined) {
       this.timer = Math.max(0, maxTimerValue * 60 - elapsedSeconds);
     } else {
       this.timer = elapsedSeconds;
@@ -179,6 +182,7 @@ export class GameRightSidebar extends LitElement implements Layer {
 
     const timerColor =
       this.game.config().gameConfig().maxTimerValue !== undefined &&
+      this.game.config().gameConfig().maxTimerValue !== null &&
       this.timer < 60
         ? "text-red-400"
         : "";
diff --git a/src/core/Schemas.ts b/src/core/Schemas.ts
index b2931dc0e..7f7b867c3 100644
--- a/src/core/Schemas.ts
+++ b/src/core/Schemas.ts
@@ -247,15 +247,15 @@ export const GameConfigSchema = z.object({
   infiniteTroops: z.boolean(),
   instantBuild: z.boolean(),
   disableNavMesh: z.boolean().optional(),
-  disableAlliances: z.boolean().optional(),
+  disableAlliances: z.boolean().nullable().optional(),
   randomSpawn: z.boolean(),
   maxPlayers: z.number().optional(),
-  maxTimerValue: z.number().int().min(1).max(120).optional(), // In minutes
-  spawnImmunityDuration: z.number().int().min(0).optional(), // In ticks
+  maxTimerValue: z.number().int().min(1).max(120).nullable().optional(), // In minutes
+  spawnImmunityDuration: z.number().int().min(0).nullable().optional(), // In ticks
   disabledUnits: z.enum(UnitType).array().optional(),
   playerTeams: TeamCountConfigSchema.optional(),
-  goldMultiplier: z.number().min(0.1).max(1000).optional(),
-  startingGold: z.number().int().min(0).max(1000000000).optional(),
+  goldMultiplier: z.number().min(0.1).max(1000).nullable().optional(),
+  startingGold: z.number().int().min(0).max(1000000000).nullable().optional(),
 });
 
 export const TeamSchema = z.string();
diff --git a/src/server/GameServer.ts b/src/server/GameServer.ts
index f6ac05e76..fbb63b925 100644
--- a/src/server/GameServer.ts
+++ b/src/server/GameServer.ts
@@ -141,7 +141,7 @@ export class GameServer {
       this.gameConfig.donateTroops = gameConfig.donateTroops;
     }
     if (gameConfig.maxTimerValue !== undefined) {
-      this.gameConfig.maxTimerValue = gameConfig.maxTimerValue;
+      this.gameConfig.maxTimerValue = gameConfig.maxTimerValue ?? undefined;
     }
     if (gameConfig.instantBuild !== undefined) {
       this.gameConfig.instantBuild = gameConfig.instantBuild;
@@ -150,7 +150,8 @@ export class GameServer {
       this.gameConfig.randomSpawn = gameConfig.randomSpawn;
     }
     if (gameConfig.spawnImmunityDuration !== undefined) {
-      this.gameConfig.spawnImmunityDuration = gameConfig.spawnImmunityDuration;
+      this.gameConfig.spawnImmunityDuration =
+        gameConfig.spawnImmunityDuration ?? undefined;
     }
     if (gameConfig.gameMode !== undefined) {
       this.gameConfig.gameMode = gameConfig.gameMode;
@@ -162,13 +163,14 @@ export class GameServer {
       this.gameConfig.playerTeams = gameConfig.playerTeams;
     }
     if (gameConfig.goldMultiplier !== undefined) {
-      this.gameConfig.goldMultiplier = gameConfig.goldMultiplier;
+      this.gameConfig.goldMultiplier = gameConfig.goldMultiplier ?? undefined;
     }
     if (gameConfig.startingGold !== undefined) {
-      this.gameConfig.startingGold = gameConfig.startingGold;
+      this.gameConfig.startingGold = gameConfig.startingGold ?? undefined;
     }
     if (gameConfig.disableAlliances !== undefined) {
-      this.gameConfig.disableAlliances = gameConfig.disableAlliances;
+      this.gameConfig.disableAlliances =
+        gameConfig.disableAlliances ?? undefined;
     }
   }