diff --git a/artiq/gateware/test/rtio/test_sed_output_driver.py b/artiq/gateware/test/rtio/test_sed_output_driver.py
index ef61b98ea..f5f038426 100644
--- a/artiq/gateware/test/rtio/test_sed_output_driver.py
+++ b/artiq/gateware/test/rtio/test_sed_output_driver.py
@@ -82,7 +82,7 @@ def simulate(input_events):
             yield
 
     run_simulation(dut, {"sys": [gen(), monitor()]},
-                   {"sys": 5, "rio": 5, "rio_phy": 5}, vcd_name="foo.vcd")
+                   {"sys": 5, "rio": 5, "rio_phy": 5})
     return output