diff --git a/tb/mdio_regs.py b/tb/mdio_regs.py
index cff6287..b9a609a 100644
--- a/tb/mdio_regs.py
+++ b/tb/mdio_regs.py
@@ -6,8 +6,7 @@ from cocotb.clock import Clock
 from cocotb.triggers import FallingEdge, Timer
 from cocotb.types import LogicArray
 
-def BIT(n):
-    return 1 << n
+from .util import BIT
 
 BMCR = 0
 BMSR = 1
diff --git a/tb/util.py b/tb/util.py
index b3a3910..aec0935 100644
--- a/tb/util.py
+++ b/tb/util.py
@@ -16,6 +16,9 @@ async def async_iter(it):
     for i in it:
         yield i
 
+def BIT(n):
+    return 1 << n
+
 # From https://stackoverflow.com/a/7864317/5086505
 class classproperty(property):
     def __get__(self, cls, owner):