diff --git a/app/static/js/nopaque.js b/app/static/js/nopaque.js
index 0301a253..bae1d8a4 100644
--- a/app/static/js/nopaque.js
+++ b/app/static/js/nopaque.js
@@ -38,6 +38,7 @@ nopaque.Forms.init = function() {
       for (let selectElement of form.querySelectorAll('select')) {
         if (selectElement.value === "") {
           parentElement = selectElement.closest(".input-field");
+          parentElement.querySelector(".select-dropdown").classList.add("invalid");
           for (let helperTextElement of parentElement.querySelectorAll(".helper-text")) {
             helperTextElement.remove();
           }