diff --git a/src/vnet/session/session.api b/src/vnet/session/session.api
index 24ebfba..aa73212 100644
--- a/src/vnet/session/session.api
+++ b/src/vnet/session/session.api
@@ -294,11 +294,13 @@
 /** \brief Unbind 
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
+    @param wrk_index - index of worker requesting the bind
     @param handle - bind handle obtained from bind reply
 */
 autoreply define unbind_sock {
   u32 client_index;
   u32 context;
+  u32 wrk_index;
   u64 handle;
 };