diff --git a/omaha_response.h b/omaha_response.h
index c702068..b973eb5 100644
--- a/omaha_response.h
+++ b/omaha_response.h
@@ -37,6 +37,7 @@
 
   // These are only valid if update_exists is true:
   std::string version;
+  std::string system_version;
 
   struct Package {
     // The ordered list of URLs in the Omaha response. Each item is a complete