diff --git a/omaha_request_action.cc b/omaha_request_action.cc
index 7eca9e0..cd31805 100644
--- a/omaha_request_action.cc
+++ b/omaha_request_action.cc
@@ -118,7 +118,8 @@
       XmlEncode(params.app_version) + "\" "
       "lang=\"" + XmlEncode(params.app_lang) + "\" track=\"" +
       XmlEncode(params.app_track) + "\" board=\"" +
-      XmlEncode(params.os_board) + "\" delta_okay=\"" +
+      XmlEncode(params.os_board) + "\" hardware_class=\"" +
+      XmlEncode(params.hardware_class) + "\" delta_okay=\"" +
       (params.delta_okay ? "true" : "false") + "\">\n" + body +
       "    </o:app>\n"
       "</o:gupdate>\n";