diff --git a/scripts/prepare_sector_network.py b/scripts/prepare_sector_network.py
index 8719c281..b8eb8bc1 100644
--- a/scripts/prepare_sector_network.py
+++ b/scripts/prepare_sector_network.py
@@ -3294,7 +3294,6 @@ def lossy_bidirectional_links(n, carrier, losses_per_thousand_km=0.0):
 
     carrier_i = n.links.query("carrier == @carrier").index
     n.links.loc[carrier_i, "p_min_pu"] = 0
-    n.links["reversed"] = False
     n.links.loc[carrier_i, "efficiency"] = (
         1 - n.links.loc[carrier_i, "length"] * losses_per_thousand_km / 1e3
     )
@@ -3302,10 +3301,11 @@ def lossy_bidirectional_links(n, carrier, losses_per_thousand_km=0.0):
         n.links.loc[carrier_i].copy().rename({"bus0": "bus1", "bus1": "bus0"}, axis=1)
     )
     rev_links.capital_cost = 0
-    rev_links.reversed = True
+    rev_links["reversed"] = True
     rev_links.index = rev_links.index.map(lambda x: x + "-reversed")
 
     n.links = pd.concat([n.links, rev_links], sort=False)
+    n.links["reversed"] = n.links["reversed"].fillna(False)
 
 
 if __name__ == "__main__":
diff --git a/scripts/solve_network.py b/scripts/solve_network.py
index a68ca074..5e8c0356 100644
--- a/scripts/solve_network.py
+++ b/scripts/solve_network.py
@@ -500,14 +500,10 @@ def add_lossy_bidirectional_link_constraints(n):
 
     carriers = n.links.loc[n.links.reversed, "carrier"].unique()
 
-    backward_i = n.links.query(
-        "carrier in @carriers and reversed and p_nom_extendable"
-    ).index
     forward_i = n.links.query(
         "carrier in @carriers and ~reversed and p_nom_extendable"
     ).index
-
-    assert len(forward_i) == len(backward_i)
+    backward_i = forward_i + "-reversed"
 
     lhs = n.model["Link-p_nom"].loc[backward_i]
     rhs = n.model["Link-p_nom"].loc[forward_i]