diff --git a/doc/go1.8.html b/doc/go1.8.html
index 337f13d630..147221a44e 100644
--- a/doc/go1.8.html
+++ b/doc/go1.8.html
@@ -1645,6 +1645,17 @@ crypto/x509: return error for missing SerialNumber (CL 27238)
       and only the overall execution of the test binary would fail.
     </p>
 
+    <p><!-- CL 32455 -->
+      The signature of the
+      <a href="/pkg/testing/#MainStart"><code>MainStart</code></a>
+      function has changed, as allowed by the documentation. It is an
+      internal detail and not part of the Go 1 compatibility promise.
+      If you're not calling <code>MainStart</code> directly but see
+      errors, that likely means you set the
+      normally-empty <code>GOROOT</code> environment variable and it
+      doesn't match the version of your <code>go</code> command's binary.
+    </p>
+
   </dd>
 </dl>