diff --git a/pfb/utils/stokes.py b/pfb/utils/stokes.py
index dd0d8ca08..7beaf16b6 100644
--- a/pfb/utils/stokes.py
+++ b/pfb/utils/stokes.py
@@ -503,11 +503,11 @@ def vfunc(gp, gq, W, V):
                 W00 = W[0]
                 W01 = 1.0
                 W10 = 1.0
-                W11 = W[3]
+                W11 = W[-1]
                 V00 = V[0]
                 V01 = 0j
                 V10 = 0j
-                V11 = V[3]
+                V11 = V[-1]
                 return Djfn(gp00, gp11,
                             gq00, gq11,
                             W00, W01, W10, W11,