diff --git a/buffet/device_registration_info.h b/buffet/device_registration_info.h
index df23e36..1985bb6 100644
--- a/buffet/device_registration_info.h
+++ b/buffet/device_registration_info.h
@@ -96,7 +96,7 @@
   // and so on. If a particular key-value pair is omitted, a default value
   // is used when possible. Returns a device claim ID on success.
   std::string StartRegistration(
-    const std::map<std::string, std::shared_ptr<base::Value>>& params,
+    const std::map<std::string, std::unique_ptr<base::Value>>& params,
     chromeos::ErrorPtr* error);
 
   // Finalizes the device registration. If |user_auth_code| is provided, then