diff --git a/src/models/leaderboardModel.ts b/src/models/leaderboardModel.ts
index 0c8cc60d..ff4753b3 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, displayName: 1 }, { unique: true });
 leaderboardEntrySchema.index({ expiry: 1 }, { expireAfterSeconds: 0 }); // With this, MongoDB will automatically delete expired entries.
 
 export const Leaderboard = model<ILeaderboardEntryDatabase>("Leaderboard", leaderboardEntrySchema);