diff --git a/app/src/main/kotlin/org/koitharu/kotatsu/local/data/MangaIndex.kt b/app/src/main/kotlin/org/koitharu/kotatsu/local/data/MangaIndex.kt
index b3f95bd00..c43a1a0a5 100644
--- a/app/src/main/kotlin/org/koitharu/kotatsu/local/data/MangaIndex.kt
+++ b/app/src/main/kotlin/org/koitharu/kotatsu/local/data/MangaIndex.kt
@@ -109,7 +109,7 @@ class MangaIndex(source: String?) {
 			jo.put(KEY_UPLOAD_DATE, chapter.value.uploadDate)
 			jo.put(KEY_SCANLATOR, chapter.value.scanlator)
 			jo.put(KEY_BRANCH, chapter.value.branch)
-			jo.put(KEY_ENTRIES, "%08d_%03d\\d{3}".format(chapter.value.branch.hashCode(), chapter.index + 1))
+			jo.put(KEY_ENTRIES, "%08d_%04d\\d{4}".format(chapter.value.branch.hashCode(), chapter.index + 1))
 			jo.put(KEY_FILE, filename)
 			chapters.put(chapter.value.id.toString(), jo)
 		}
diff --git a/app/src/main/kotlin/org/koitharu/kotatsu/local/data/output/LocalMangaDirOutput.kt b/app/src/main/kotlin/org/koitharu/kotatsu/local/data/output/LocalMangaDirOutput.kt
index 0a98d02b0..6fabb761f 100644
--- a/app/src/main/kotlin/org/koitharu/kotatsu/local/data/output/LocalMangaDirOutput.kt
+++ b/app/src/main/kotlin/org/koitharu/kotatsu/local/data/output/LocalMangaDirOutput.kt
@@ -162,6 +162,6 @@ class LocalMangaDirOutput(
 
 	companion object {
 
-		private const val FILENAME_PATTERN = "%08d_%03d%03d"
+		private const val FILENAME_PATTERN = "%08d_%04d%04d"
 	}
 }
diff --git a/app/src/main/kotlin/org/koitharu/kotatsu/local/data/output/LocalMangaZipOutput.kt b/app/src/main/kotlin/org/koitharu/kotatsu/local/data/output/LocalMangaZipOutput.kt
index 56afe27fe..3d6767b9a 100644
--- a/app/src/main/kotlin/org/koitharu/kotatsu/local/data/output/LocalMangaZipOutput.kt
+++ b/app/src/main/kotlin/org/koitharu/kotatsu/local/data/output/LocalMangaZipOutput.kt
@@ -118,7 +118,7 @@ class LocalMangaZipOutput(
 
 	companion object {
 
-		private const val FILENAME_PATTERN = "%08d_%03d%03d"
+		private const val FILENAME_PATTERN = "%08d_%04d%04d"
 
 		suspend fun filterChapters(file: File, manga: Manga, idsToRemove: Set<Long>) =
 			runInterruptible(Dispatchers.IO) {