diff --git a/src/core/transport/transport.h b/src/core/transport/transport.h
index cdea0b9..7a389ea 100644
--- a/src/core/transport/transport.h
+++ b/src/core/transport/transport.h
@@ -76,6 +76,9 @@
 
   grpc_status_code cancel_with_status;
   grpc_mdstr *cancel_message;
+
+  /* Indexes correspond to grpc_context_index enum values */
+  void *const *context;
 } grpc_transport_op;
 
 /* Callbacks made from the transport to the upper layers of grpc. */