diff --git a/test/unit/lazy-upgrade.html b/test/unit/lazy-upgrade.html
index 8359136f63..1e34db7ce2 100644
--- a/test/unit/lazy-upgrade.html
+++ b/test/unit/lazy-upgrade.html
@@ -43,6 +43,10 @@
 <dom-module id="lazy-child">
   <template>
     <style>
+      /* Work around IE/Edge bug with :not([attr]) */
+      :host([disable-upgrade]) {
+        display: block;
+      }
       :host(:not([disable-upgrade])) {
         display: block;
         border: 2px solid blue;