diff --git a/url.bs b/url.bs
index 2bd45d1d..7b388cf8 100644
--- a/url.bs
+++ b/url.bs
@@ -1897,7 +1897,8 @@ string <var>input</var>, optionally with a <a>base URL</a> <var>base</var>, opti
       <ol>
        <li>
         <p>If <var>base</var> is non-null and <var>base</var>'s <a for=url>scheme</a> is
-        "<code>file</code>", then:
+        "<code>file</code>" and the substring from <var>pointer</var> in the <var>input</var> does
+        not <a lt="starts with Windows drive letter">start with Windows drive letter</a>, then:
 
         <ol>
          <li>