diff --git a/migen/actorlib/structuring.py b/migen/actorlib/structuring.py
index 6f6483b28..dbe2204ab 100644
--- a/migen/actorlib/structuring.py
+++ b/migen/actorlib/structuring.py
@@ -8,14 +8,20 @@ def _rawbits_layout(l):
 		return l
 
 class Cast(CombinatorialActor):
-	def __init__(self, layout_from, layout_to):
+	def __init__(self, layout_from, layout_to, reverse_from=False, reverse_to=False):
+		self.reverse_from = reverse_from
+		self.reverse_to = reverse_to
 		CombinatorialActor.__init__(self,
 			("sink", Sink, _rawbits_layout(layout_from)),
 			("source", Source, _rawbits_layout(layout_to)))
 	
 	def get_process_fragment(self):
 		sigs_from = self.token("sink").flatten()
+		if self.reverse_from:
+			sigs_from = list(reversed(sigs_from))
 		sigs_to = self.token("source").flatten()
+		if self.reverse_to:
+			sigs_to = list(reversed(sigs_to))
 		if sum(len(s) for s in sigs_from) != sum(len(s) for s in sigs_to):
 			raise TypeError
 		return Fragment([