diff --git a/test/runner.html b/test/runner.html
index ad9d00e356..fdd567b492 100644
--- a/test/runner.html
+++ b/test/runner.html
@@ -98,7 +98,7 @@
     }
 
     // test shadowdom/custom elements polyfills together
-    // prefering both if possible.
+    // preferring both if possible.
     var matrix = [''];
     var webcomponents = '';
     if (window.customElements) {