diff --git a/app/src/main/java/eu/kanade/tachiyomi/data/backup/full/models/BackupCategory.kt b/app/src/main/java/eu/kanade/tachiyomi/data/backup/full/models/BackupCategory.kt
index 27bc4d354e..856b4abe03 100644
--- a/app/src/main/java/eu/kanade/tachiyomi/data/backup/full/models/BackupCategory.kt
+++ b/app/src/main/java/eu/kanade/tachiyomi/data/backup/full/models/BackupCategory.kt
@@ -14,7 +14,7 @@ class BackupCategory(
     @ProtoNumber(100) var flags: Int = 0,
 
     // J2K Specific values
-    @ProtoNumber(800) var mangaSort: Char?,
+    @ProtoNumber(800) var mangaSort: Char? = null,
 ) {
     fun getCategoryImpl(): CategoryImpl {
         return CategoryImpl().apply {