diff --git a/protocol/wayland.xml b/protocol/wayland.xml
index 54fb9e02..b6beceb7 100644
--- a/protocol/wayland.xml
+++ b/protocol/wayland.xml
@@ -365,7 +365,7 @@
       <arg name="surface" type="object" interface="wl_surface"/>
       <arg name="x" type="fixed"/>
       <arg name="y" type="fixed"/>
-      <arg name="id" type="object" interface="wl_data_offer"/>
+      <arg name="id" type="object" interface="wl_data_offer" allow-null="true"/>
     </event>
 
     <event name="leave"/>