diff --git a/model_data/simulation_system/app.py b/model_data/simulation_system/app.py
index 545fae16..f0df75e4 100644
--- a/model_data/simulation_system/app.py
+++ b/model_data/simulation_system/app.py
@@ -86,7 +86,7 @@ HEAT_DEMAND_RESPONSE = "ENERGY_CONSUMPTION_CURRENT"
 def make_cleaning_averages(df):
     # Define a custom function to calculate the median, excluding missing values
     def median_without_missing(group):
-        return group[AVERAGE_FIXED_FEATURES].dropna().median()
+        return group[AVERAGE_FIXED_FEATURES].median(skipna=True)
 
     cleaning_averages = df.groupby(
         ["PROPERTY_TYPE", "BUILT_FORM", "CONSTRUCTION_AGE_BAND", "NUMBER_HABITABLE_ROOMS", "NUMBER_HEATED_ROOMS"],