diff --git a/src/main/java/de/grimsi/gameyfin/repositories/DetectedGameRepository.java b/src/main/java/de/grimsi/gameyfin/repositories/DetectedGameRepository.java
index 0122f07..78ac2d0 100644
--- a/src/main/java/de/grimsi/gameyfin/repositories/DetectedGameRepository.java
+++ b/src/main/java/de/grimsi/gameyfin/repositories/DetectedGameRepository.java
@@ -6,4 +6,5 @@ import org.springframework.data.jpa.repository.JpaRepository;
 public interface DetectedGameRepository extends JpaRepository<DetectedGame, String> {
 
     boolean existsByPath(String path);
+    boolean existsBySlug(String slug);
 }
diff --git a/src/main/java/de/grimsi/gameyfin/service/GameService.java b/src/main/java/de/grimsi/gameyfin/service/GameService.java
index 6ff55f6..d9679ff 100644
--- a/src/main/java/de/grimsi/gameyfin/service/GameService.java
+++ b/src/main/java/de/grimsi/gameyfin/service/GameService.java
@@ -36,9 +36,13 @@ public class GameService {
     }
 
     public DetectedGame mapUnmappedFile(Long unmappedGameId, String igdbSlug) {
+
         UnmappableFile unmappableFile = unmappableFileRepository.findById(unmappedGameId)
                 .orElseThrow(() -> new ResponseStatusException(HttpStatus.NOT_FOUND, "Unmapped file with id '%d' does not exist.".formatted(unmappedGameId)));
 
+        if(detectedGameRepository.existsBySlug(igdbSlug))
+            throw new ResponseStatusException(HttpStatus.CONFLICT, "Game with slug '%s' already exists in database.".formatted(igdbSlug));
+
         Igdb.Game igdbGame = igdbWrapper.getGameBySlug(igdbSlug)
                 .orElseThrow(() -> new ResponseStatusException(HttpStatus.NOT_FOUND, "Game with slug '%s' does not exist on IGDB.".formatted(igdbSlug)));