diff --git a/src/battle-scene.ts b/src/battle-scene.ts
index 271cde1aaa9..5905cb66cde 100644
--- a/src/battle-scene.ts
+++ b/src/battle-scene.ts
@@ -1514,7 +1514,7 @@ export class BattleScene extends SceneBase {
   }
 
   newArena(biome: BiomeId, playerFaints?: number): Arena {
-    this.arena = new Arena(biome, BiomeId[biome].toLowerCase(), playerFaints);
+    this.arena = new Arena(biome, playerFaints);
     this.eventTarget.dispatchEvent(new NewArenaEvent());
 
     this.arenaBg.pipelineData = {
diff --git a/src/field/arena.ts b/src/field/arena.ts
index 06ba6fdd334..a4744f38769 100644
--- a/src/field/arena.ts
+++ b/src/field/arena.ts
@@ -68,9 +68,9 @@ export class Arena {
 
   public readonly eventTarget: EventTarget = new EventTarget();
 
-  constructor(biome: BiomeId, bgm: string, playerFaints = 0) {
+  constructor(biome: BiomeId, playerFaints = 0) {
     this.biomeType = biome;
-    this.bgm = bgm;
+    this.bgm = BiomeId[biome].toLowerCase();
     this.trainerPool = biomeTrainerPools[biome];
     this.updatePoolsForTimeOfDay();
     this.playerTerasUsed = 0;