diff --git a/src/tea3/tea3model.py b/src/tea3/tea3model.py
index 37bb0aa..3e5d4fa 100644
--- a/src/tea3/tea3model.py
+++ b/src/tea3/tea3model.py
@@ -65,7 +65,7 @@ def xor_vec(a, b):
     return [ai + bi for ai, bi in zip(a, b)]
 
 def BP(r):
-    return [r[2], r[7], r[3], r[5], r[6], r[1], r[0], r[4]]
+    return [r[3], r[7], r[6], r[1], r[2], r[4], r[0], r[5]]
 
 def F31(X, Y):
     x0, x1, x2, x3, x4, x5, x6, x7 = X