diff --git a/ofdm/fdet_eval.m b/ofdm/fdet_eval.m
index d67490e..8656be7 100644
--- a/ofdm/fdet_eval.m
+++ b/ofdm/fdet_eval.m
@@ -27,11 +27,10 @@ for k=1:K
     err(k) = f_f;
     f_est = f_est + f_f;
     dphi_est = 2*pi*mod(f_est/fs*N, 1);
-    phi_est = phi_est + dphi_est;
+    phi_est = mod(phi_est + dphi_est, 2*pi);
 end;
 
 f_est = f_est
-
 error_ppm = 1E6*(1-f_est/f_true)