diff --git a/litex/soc/cores/code_8b10b.py b/litex/soc/cores/code_8b10b.py
index 8ae45202e..7e850d2f1 100644
--- a/litex/soc/cores/code_8b10b.py
+++ b/litex/soc/cores/code_8b10b.py
@@ -30,6 +30,9 @@ from litex.soc.interconnect import stream
 def K(x, y):
     return (y << 5) | x
 
+def D(x, y):
+    return (y << 5) | x
+
 def disparity(word, nbits):
     n0 = 0
     n1 = 0