diff --git a/devenv/docker/loadtest/modules/client.js b/devenv/docker/loadtest/modules/client.js
index 86e923823db..72e66476a46 100644
--- a/devenv/docker/loadtest/modules/client.js
+++ b/devenv/docker/loadtest/modules/client.js
@@ -8,7 +8,7 @@ export const UIEndpoint = class UIEndpoint {
 
   login(username, pwd) {
     const payload = { user: username, password: pwd };
-    return this.httpClient.formPost('/login', payload);
+    return this.httpClient.post('/login', JSON.stringify(payload));
   }
 };