diff --git a/tutorials/compositionPlots.py b/tutorials/compositionPlots.py
index c851975..d032379 100644
--- a/tutorials/compositionPlots.py
+++ b/tutorials/compositionPlots.py
@@ -128,6 +128,7 @@ def determine_carbon_number(compound):
 plt.tight_layout()
 
 # Plot pie chart of family weights
+family_names = family_weights.index.tolist()
 plt.figure(figsize=(7, 5))
 plt.pie(
     family_weights,