diff --git a/app/src/main/java/eu/kanade/tachiyomi/ui/manga/MangaScreenModel.kt b/app/src/main/java/eu/kanade/tachiyomi/ui/manga/MangaScreenModel.kt
index 44cf40abc..9fdbed325 100644
--- a/app/src/main/java/eu/kanade/tachiyomi/ui/manga/MangaScreenModel.kt
+++ b/app/src/main/java/eu/kanade/tachiyomi/ui/manga/MangaScreenModel.kt
@@ -544,6 +544,9 @@ class MangaInfoScreenModel(
 
             return originalManga
         } else {
+            if (manga.id == originalMangaId) {
+                throw IllegalArgumentException(context.getString(R.string.merged_already))
+            }
             var mergedManga = Manga.create()
                 .copy(
                     url = originalManga.url,