diff --git a/migen/genlib/crc.py b/migen/genlib/crc.py
index 51a9ab108..0c5714785 100644
--- a/migen/genlib/crc.py
+++ b/migen/genlib/crc.py
@@ -1,3 +1,4 @@
+from collections import OrderedDict
 from migen.fhdl.std import *
 from migen.genlib.misc import optree
 
@@ -37,7 +38,7 @@ class CRCEngine(Module):
 			Replace even numbers of XORs in the equation
 			with an equivalent XOR
 			"""
-			d = {}
+			d = OrderedDict()
 			for e in l:
 				if e in d:
 					d[e] += 1