diff --git a/rtl_lib/gearbox.py b/rtl_lib/gearbox.py
index 313a8c81399ac4243afcdaf687426c52b36bdb94..5d5c63a68f5450f0e9925dd755db4115b42b276f 100644
--- a/rtl_lib/gearbox.py
+++ b/rtl_lib/gearbox.py
@@ -221,8 +221,8 @@ class DummyPlug(Elaboratable):
         m = Module()
 
         upstream_width   = 3
-        downstream_width = 41
-        sim_memory_size = 256
+        downstream_width = 17
+        sim_memory_size = 64
 
         expiration_date = sim_memory_size - upstream_width*2