diff --git a/test/test_axi_lite.py b/test/test_axi_lite.py
index c350e6488..6380e3e3f 100644
--- a/test/test_axi_lite.py
+++ b/test/test_axi_lite.py
@@ -70,7 +70,7 @@ class TestAXILite(unittest.TestCase):
             for _ in range(8):
                 yield
         dut = AXILiteDUT()
-        run_simulation(dut, generator(dut.dut), vcd_name='axi-write-read.vcd')
+        run_simulation(dut, generator(dut.dut))
 
     def test_simultaneous(dut):
         def generator(dut):
@@ -101,4 +101,4 @@ class TestAXILite(unittest.TestCase):
 
 
         dut = AXILiteDUT()
-        run_simulation(dut, generator(dut.dut), vcd_name='axi-simultaneous.vcd')
+        run_simulation(dut, generator(dut.dut))
diff --git a/test/test_gearbox.py b/test/test_gearbox.py
index cf444d0bf..7bb748cff 100644
--- a/test/test_gearbox.py
+++ b/test/test_gearbox.py
@@ -51,5 +51,5 @@ class TestGearbox(unittest.TestCase):
             data_generator(dut, dut.gearbox0, datas),
             data_checker(dut, dut.gearbox1, datas)
         ]
-        run_simulation(dut, generators, vcd_name="sim.vcd")
+        run_simulation(dut, generators)
         self.assertEqual(dut.errors, 0)