diff --git a/vpr/src/route/route_tree_timing.cpp b/vpr/src/route/route_tree_timing.cpp
index 0e1ac4f..7988d02 100644
--- a/vpr/src/route/route_tree_timing.cpp
+++ b/vpr/src/route/route_tree_timing.cpp
@@ -1370,6 +1370,8 @@
             return false;
         }
 
+        C_downstream_children += device_ctx.rr_switch_inf[edge->iswitch].Cinternal;
+
         if (!device_ctx.rr_switch_inf[edge->iswitch].buffered()) {
             C_downstream_children += edge->child->C_downstream;
         }