diff --git a/star_chart_spherical_projection/generate_star_chart.py b/star_chart_spherical_projection/generate_star_chart.py
index b7a96c2..4726a10 100644
--- a/star_chart_spherical_projection/generate_star_chart.py
+++ b/star_chart_spherical_projection/generate_star_chart.py
@@ -362,7 +362,7 @@ def plot_stereographic_projection(included_stars=[],
                                                                         pole)
 
     # Display declination lines on the chart from -min to +max
-    def displayDeclinationMarksOnAxis(declination_values, dec_min, dec_max, isInverted):
+    def displayDeclinationMarksOnAxis(declination_values, dec_min, dec_max, is_inverted):
         # set declination marks based on the ruler to space out lines
         ruler_declination_position = list(ruler_position_dict.values())
         ruler_declination_labels = list(ruler_position_dict.keys())