diff --git a/scripts/map_consensus.py b/scripts/map_consensus.py
index 1d09207bf3..a95b7ef249 100644
--- a/scripts/map_consensus.py
+++ b/scripts/map_consensus.py
@@ -5,7 +5,7 @@
 from matplotlib.pyplot import cm
 
 
-def extract_data(filepath):
+def extract_data(filepath) -> None:
     """
     Extracts the emission data from a text file.
 
@@ -58,7 +58,7 @@ def extract_data(filepath):
     return data
 
 
-def visualize_data(emission_data, output_filename="consensus_plot.svg"):
+def visualize_data(emission_data, output_filename="consensus_plot.svg") -> None:
     """
     Generates and saves a contour plot of the retention map.