diff --git a/src/utils/stringUtils.ts b/src/utils/stringUtils.ts
index d3d50d9..b6ed6dd 100644
--- a/src/utils/stringUtils.ts
+++ b/src/utils/stringUtils.ts
@@ -8,7 +8,7 @@ import { CLIENT_ERROR } from '../errors';
  */
 export function valuesToStringList(values: ItemStatusResponse): string[] {
   try {
-    return (values['sumstate']['value'] as string).slice(0, -1).split(';');
+    return values.sumstate.value.slice(0, -1).split(';');
   } catch (e) {
     throw new Error(CLIENT_ERROR.CANNOT_PARSE_STATUS);
   }
diff --git a/test/utils/stringUtils.test.ts b/test/utils/stringUtils.test.ts
index dd65175..c9844ee 100644
--- a/test/utils/stringUtils.test.ts
+++ b/test/utils/stringUtils.test.ts
@@ -1,3 +1,4 @@
+import { ItemStatusResponse, SystemStatusResponse } from '../../src/client';
 import { CLIENT_ERROR } from '../../src/errors';
 import {
   systemFilteredByGroup,
@@ -6,15 +7,23 @@ import {
 } from '../../src/utils/stringUtils';
 
 test('valuesToStringList', () => {
-  expect(valuesToStringList(JSON.parse('{"sumstate":{"value":"0;0;3;kW;10.001;"}}'), null)).toEqual(
-    ['0', '0', '3', 'kW', '10.001']
-  );
-  expect(
-    valuesToStringList(JSON.parse('{"item0":{"sumstate":{"value":"0;0;3;C°;199.999;"}}}'), 'item0')
-  ).toEqual(['0', '0', '3', 'C°', '199.999']);
+  expect(valuesToStringList(JSON.parse('{"sumstate":{"value":"0;0;3;kW;10.001;"}}'))).toEqual([
+    '0',
+    '0',
+    '3',
+    'kW',
+    '10.001',
+  ]);
+  expect(valuesToStringList({ sumstate: { value: '0;0;3;C°;199.999;' } })).toEqual([
+    '0',
+    '0',
+    '3',
+    'C°',
+    '199.999',
+  ]);
 
   expect(() => {
-    valuesToStringList(JSON.parse('{"item0":{"sumstate":{"value":"0;0;0;0;0;"}}}'), 'item1');
+    valuesToStringList(JSON.parse('{}'));
   }).toThrow(CLIENT_ERROR.CANNOT_PARSE_STATUS);
 });