diff --git a/test/load/vm-lifecycle.js b/test/load/vm-lifecycle.js
index 367be8d..5ac6b38 100644
--- a/test/load/vm-lifecycle.js
+++ b/test/load/vm-lifecycle.js
@@ -8,7 +8,7 @@ import {expect} from 'https://jslib.k6.io/k6-testing/0.6.1/index.js';
 
 const BASE_URL = __ENV.BASE_URL || 'http://127.0.0.1:6120/v1';
 const WS_BASE_URL = __ENV.WS_BASE_URL || BASE_URL.replace(/^http/, 'ws');
-const WS_BYTES = __ENV.WS_BYTES || 64 * 1024;
+const WS_BYTES = Number(__ENV.WS_BYTES) || 64 * 1024;
 const SERVICE_ACCOUNT_NAME = __ENV.SERVICE_ACCOUNT_NAME;
 const SERVICE_ACCOUNT_TOKEN = __ENV.SERVICE_ACCOUNT_TOKEN;