diff --git a/lib/validators/belgiumBallotValidator.ts b/lib/validators/belgiumBallotValidator.ts
index 344dc5e7..74bbc19c 100644
--- a/lib/validators/belgiumBallotValidator.ts
+++ b/lib/validators/belgiumBallotValidator.ts
@@ -1,4 +1,5 @@
 import { ContestContent, OptionSelection, SelectionPile } from '../av_client/types';
+import { Error } from "../av_client/types"
 
 class BelgiumBallotValidator {
   private contest: ContestContent;
@@ -6,10 +7,10 @@ class BelgiumBallotValidator {
     this.contest = contest;
   }
 
-  validate(selectionPile: SelectionPile): string[] {
-    const errors: string[] = [];
+  validate(selectionPile: SelectionPile): Error[] {
+    const errors: Error[] = [];
 
-    if (this.partyExclusive(selectionPile.optionSelections)) errors.push('cross_party_voting');
+    if (this.partyExclusive(selectionPile.optionSelections)) errors.push({ message: 'cross_party_voting' });
 
     return errors
   }
diff --git a/package.json b/package.json
index 56858cb2..b37b1515 100644
--- a/package.json
+++ b/package.json
@@ -1,5 +1,5 @@
 {
-  "version": "4.0.0",
+  "version": "4.0.1",
   "name": "@aion-dk/js-client",
   "license": "MIT",
   "description": "Assembly Voting JS client",