diff --git a/scripts/prepare_network.py b/scripts/prepare_network.py
index 17a9b4e4..e98d9ff1 100644
--- a/scripts/prepare_network.py
+++ b/scripts/prepare_network.py
@@ -31,9 +31,9 @@ def add_emission_prices(n, emission_prices=None, exclude_co2=False):
     n.storage_units['marginal_cost'] += n.storage_units.carrier.map(ep)
 
 def set_line_s_max_pu(n):
-    # set n-1 security margin to 0.5 for 45 clusters and to 0.7 from 200 clusters
+    # set n-1 security margin to 0.5 for 37 clusters and to 0.7 from 200 clusters
     n_clusters = len(n.buses)
-    s_max_pu = np.clip(0.5 + 0.2 * (n_clusters - 45) / (200 - 45), 0.5, 0.7)
+    s_max_pu = np.clip(0.5 + 0.2 * (n_clusters - 37) / (200 - 45), 0.5, 0.7)
     n.lines['s_max_pu'] = s_max_pu
 
     dc_b = n.links.carrier == 'DC'