diff --git a/liteeth/mac/__init__.py b/liteeth/mac/__init__.py
index 86da1bb..548d882 100644
--- a/liteeth/mac/__init__.py
+++ b/liteeth/mac/__init__.py
@@ -50,7 +50,7 @@ class LiteEthMAC(Module, AutoCSR):
             self.tx_slots  = CSRConstant(ntxslots)
             self.slot_size = CSRConstant(2**bits_for(eth_mtu))
             wishbone_interface = LiteEthMACWishboneInterface(
-                dw         = 32,
+                dw         = dw,
                 nrxslots   = nrxslots,
                 ntxslots   = ntxslots,
                 endianness = endianness,