diff --git a/www/common/common-interface.js b/www/common/common-interface.js
index 7b05d22fe..75db27ea3 100644
--- a/www/common/common-interface.js
+++ b/www/common/common-interface.js
@@ -1,3 +1,11 @@
+if (!document.querySelector("#alertifyCSS")) {
+    // Prevent alertify from injecting CSS, we create our own in alertify.less.
+    var head = document.getElementsByTagName("head")[0];
+    var css = document.createElement("span");
+    css.id = "alertifyCSS";
+    css.setAttribute('data-but-why', 'see: common-interface.js');
+    head.insertBefore(css, head.firstChild);
+}
 define([
     'jquery',
     '/customize/messages.js',