diff --git a/topology.yaml b/topology.yaml
index e1238d4..7e64d45 100644
--- a/topology.yaml
+++ b/topology.yaml
@@ -1,6 +1,7 @@
 
 system:
   ns_per_mm: 0.01   # wire propagation delay: 10 ps/mm (on-chip silicon)
+  flit_bytes: 4096  # wire chunk size (ADR-0033 D1: multiple of hbm_ctrl.burst_bytes=256)
 
   sips:
     count: 2