diff --git a/nafuma/electrochemistry/plot.py b/nafuma/electrochemistry/plot.py
index 9ab421f..8c7f860 100644
--- a/nafuma/electrochemistry/plot.py
+++ b/nafuma/electrochemistry/plot.py
@@ -618,9 +618,9 @@ def generate_colours(options):
 		discharge_colour = options['colours'][1]
 
 		if isinstance(charge_colour, tuple):
-			charge_colour = [charge_colour]
+			charge_colour = list(charge_colour)
 		if isinstance(discharge_colour, tuple):
-			discharge_colour = [discharge_colour]
+			discharge_colour = list(discharge_colour)
 	
 	else:
 		charge_colour = [(40/255, 70/255, 75/255)] # Dark Slate Gray #28464B, coolors.co