diff --git a/src/models/leaderboardModel.ts b/src/models/leaderboardModel.ts
index 6ff6d53a..7cd9d1e7 100644
--- a/src/models/leaderboardModel.ts
+++ b/src/models/leaderboardModel.ts
@@ -13,6 +13,7 @@ const leaderboardEntrySchema = new Schema<ILeaderboardEntryDatabase>(
 );
 
 leaderboardEntrySchema.index({ leaderboard: 1 });
+leaderboardEntrySchema.index({ leaderboard: 1, accountId: 1 }, { unique: true });
 leaderboardEntrySchema.index({ expiry: 1 }, { expireAfterSeconds: 0 }); // With this, MongoDB will automatically delete expired entries.
 
 export const Leaderboard = model<ILeaderboardEntryDatabase>("Leaderboard", leaderboardEntrySchema);
diff --git a/src/services/leaderboardService.ts b/src/services/leaderboardService.ts
index a8d933f7..72110b37 100644
--- a/src/services/leaderboardService.ts
+++ b/src/services/leaderboardService.ts
@@ -20,8 +20,8 @@ export const submitLeaderboardScore = async (
         expiry = new Date(weekEnd);
     }
     await Leaderboard.findOneAndUpdate(
-        { leaderboard, displayName },
-        { $max: { score }, $set: { accountId, expiry } },
+        { leaderboard, accountId },
+        { $max: { score }, $set: { displayName, expiry } },
         { upsert: true }
     );
 };