diff --git a/src/main/java/de/deadlocker8/budgetmaster/database/model/BackupDatabase.java b/src/main/java/de/deadlocker8/budgetmaster/database/model/BackupDatabase.java
index fdb8d0678e9820b7a88110745a819ff741b9208e..a3e15926c4ba3fc3ae76bd919f618f0168b0ffba 100644
--- a/src/main/java/de/deadlocker8/budgetmaster/database/model/BackupDatabase.java
+++ b/src/main/java/de/deadlocker8/budgetmaster/database/model/BackupDatabase.java
@@ -2,6 +2,9 @@ package de.deadlocker8.budgetmaster.database.model;
 
 import de.deadlocker8.budgetmaster.database.InternalDatabase;
 
+import java.util.ArrayList;
+import java.util.List;
+
 public interface BackupDatabase
 {
 	int getVersion();
@@ -9,4 +12,14 @@ public interface BackupDatabase
 	BackupDatabase upgrade();
 
 	InternalDatabase convertToInternal();
+
+	default <T> List<T> upgradeItems(List<? extends Upgradeable<T>> items)
+	{
+		List<T> upgradedItems = new ArrayList<>();
+		for(Upgradeable<T> item : items)
+		{
+			upgradedItems.add(item.upgrade());
+		}
+		return upgradedItems;
+	}
 }
diff --git a/src/main/java/de/deadlocker8/budgetmaster/database/model/v4/BackupDatabase_v4.java b/src/main/java/de/deadlocker8/budgetmaster/database/model/v4/BackupDatabase_v4.java
index 034f3717b53b8ccf9f7f53b1341f9988d5e8dd80..4214cb37b76a3c80972b188fd9156be006dfa26f 100644
--- a/src/main/java/de/deadlocker8/budgetmaster/database/model/v4/BackupDatabase_v4.java
+++ b/src/main/java/de/deadlocker8/budgetmaster/database/model/v4/BackupDatabase_v4.java
@@ -3,7 +3,6 @@ package de.deadlocker8.budgetmaster.database.model.v4;
 import de.deadlocker8.budgetmaster.database.InternalDatabase;
 import de.deadlocker8.budgetmaster.database.JSONIdentifier;
 import de.deadlocker8.budgetmaster.database.model.BackupDatabase;
-import de.deadlocker8.budgetmaster.database.model.Upgradeable;
 import de.deadlocker8.budgetmaster.database.model.v5.BackupDatabase_v5;
 
 import java.util.ArrayList;
@@ -95,16 +94,6 @@ public class BackupDatabase_v4 implements BackupDatabase
 		return upgradedDatabase;
 	}
 
-	private <T> List<T> upgradeItems(List<? extends Upgradeable<T>> items)
-	{
-		List<T> upgradedItems = new ArrayList<>();
-		for(Upgradeable<T> item : items)
-		{
-			upgradedItems.add(item.upgrade());
-		}
-		return upgradedItems;
-	}
-
 	@Override
 	public InternalDatabase convertToInternal()
 	{