diff --git a/kat_test/random/freq_noise_pdh.kat b/kat_test/random/freq_noise_pdh.kat
index b0229dcbbbbc277669ad89b489b2f1e120b9d513..7696f922a047f6cf5dd66906abb7317cb8051cda 100644
--- a/kat_test/random/freq_noise_pdh.kat
+++ b/kat_test/random/freq_noise_pdh.kat
@@ -10,7 +10,7 @@ s s0 0 ni n0
 # PDH modulation
 mod EO 10M 0.01 1 pm n0 n1_1
 s s1 0 n1_1 n1_2
-
+conf EO numerical_f_couple 1
 # Definition of nearly all-reflective cavity.
 m m1 0.99 0.01 0 n1_2 n2 # mirror R=0.99 T=0.01, phi=0
 s s1 2.99792458 n2 n3 # space L=c*10ns
@@ -32,4 +32,4 @@ put reflected f2 $x1
 
 yaxis db:deg # plot gain in dB and phase
 
-#gnuterm no
+gnuterm no