diff --git a/src/main/java/cc/fascinated/backend/model/score/Score.java b/src/main/java/cc/fascinated/backend/model/score/Score.java
index 8c5fe16..bcb8f53 100644
--- a/src/main/java/cc/fascinated/backend/model/score/Score.java
+++ b/src/main/java/cc/fascinated/backend/model/score/Score.java
@@ -19,7 +19,7 @@ import java.util.List;
  * A score for an account.
  */
 @Document
-@CompoundIndex(name = "accountId_leaderboardId", def = "{'accountId' : 1, 'leaderboardId' : 1}")
+@CompoundIndex(name = "accountId_leaderboardId", def = "{'accountId' : 1, 'leaderboardId' : 1}", unique = true)
 @AllArgsConstructor @Getter @Setter
 public class Score {
     /**