diff --git a/litedram/frontend/bist.py b/litedram/frontend/bist.py
index 5234e7f..c18aa12 100644
--- a/litedram/frontend/bist.py
+++ b/litedram/frontend/bist.py
@@ -171,7 +171,7 @@ class _LiteDRAMBISTChecker(Module, AutoCSR):
 
 
 class LiteDRAMBISTChecker(Module, AutoCSR):
-    def __init__(self, dram_port, cd="sys"):
+    def __init__(self, dram_port):
         self.reset = CSRStorage()
         self.shoot = CSR()
         self.done = CSRStatus()
@@ -181,6 +181,8 @@ class LiteDRAMBISTChecker(Module, AutoCSR):
 
         # # #
 
+        cd = dram_port.cd
+
         checker = ResetInserter()(_LiteDRAMBISTChecker(dram_port))
         self.submodules += ClockDomainsRenamer(cd)(checker)