diff --git a/cost_function.py b/cost_function.py
index 55536e89c34d387f2a22fdb82230d4707c2e41ff..bb5ea8137588032b07bd5336d011395c3295f377 100755
--- a/cost_function.py
+++ b/cost_function.py
@@ -270,8 +270,8 @@ for edge in g.edges():
         Delta_Ro = g.vp.last_av_ros[source_node] \
             - g.vp.first_av_ros[target_node]
     else:
-        print("At least one of the rossbies is invalid.")
-        #Delta_Ro = delta_ro_mean
+        # At least one of the rossbies is invalid.
+        # Delta_Ro = delta_ro_mean
         Delta_Ro = 0
 
     # Calculate the second term