diff --git a/scripts/add_electricity.py b/scripts/add_electricity.py
index 17e030b4..49510953 100755
--- a/scripts/add_electricity.py
+++ b/scripts/add_electricity.py
@@ -852,7 +852,7 @@ if __name__ == "__main__":
         fuel_price = pd.read_csv(
             snakemake.input.fuel_price, index_col=0, header=0, parse_dates=True
         )
-        fuel_price = fuel_price.reindex(n.snapshots).fillna(method="ffill")
+        fuel_price = fuel_price.reindex(n.snapshots).ffill()
     else:
         fuel_price = None
 
diff --git a/scripts/make_summary_perfect.py b/scripts/make_summary_perfect.py
index 76bd4ad0..8e56e5d4 100644
--- a/scripts/make_summary_perfect.py
+++ b/scripts/make_summary_perfect.py
@@ -631,7 +631,7 @@ def calculate_co2_emissions(n, label, df):
     weightings = n.snapshot_weightings.generators.mul(
         n.investment_period_weightings["years"]
         .reindex(n.snapshots)
-        .fillna(method="bfill")
+        .bfill()
         .fillna(1.0),
         axis=0,
     )
diff --git a/scripts/prepare_network.py b/scripts/prepare_network.py
index 00cb00bf..382e633d 100755
--- a/scripts/prepare_network.py
+++ b/scripts/prepare_network.py
@@ -137,9 +137,7 @@ def add_emission_prices(n, emission_prices={"co2": 0.0}, exclude_co2=False):
 def add_dynamic_emission_prices(n):
     co2_price = pd.read_csv(snakemake.input.co2_price, index_col=0, parse_dates=True)
     co2_price = co2_price[~co2_price.index.duplicated()]
-    co2_price = (
-        co2_price.reindex(n.snapshots).fillna(method="ffill").fillna(method="bfill")
-    )
+    co2_price = co2_price.reindex(n.snapshots).ffill().bfill()
 
     emissions = (
         n.generators.carrier.map(n.carriers.co2_emissions) / n.generators.efficiency