diff --git a/demos/wiener_filter_easy.py b/demos/wiener_filter_easy.py
index a0a30eb24adcbb51ca7b33adf9cb65647523876d..9ed7be0bf61c3b4134db02ba23170e3be3e53b14 100644
--- a/demos/wiener_filter_easy.py
+++ b/demos/wiener_filter_easy.py
@@ -57,7 +57,8 @@ if __name__ == "__main__":
     IC = ift.GradientNormController(verbose=True, iteration_limit=500,
                                     tol_abs_gradnorm=0.1)
     inverter = ift.ConjugateGradient(controller=IC)
-    D = (R.adjoint*N.inverse*R + fft.adjoint*Sh.inverse*fft).inverse
+    S_inv = fft.adjoint*Sh.inverse*fft
+    D = (R.adjoint*N.inverse*R + S_inv).inverse
     # MR FIXME: we can/should provide a preconditioner here as well!
     D = ift.InversionEnabler(D, inverter)
     m = D(j)