diff --git a/backtesting/_plotting.py b/backtesting/_plotting.py
index 844318aa..4b93b4be 100644
--- a/backtesting/_plotting.py
+++ b/backtesting/_plotting.py
@@ -88,7 +88,7 @@ def colorgen():
 def lightness(color, lightness=.94):
     rgb = np.array([color.r, color.g, color.b]) / 255
     h, _, s = rgb_to_hls(*rgb)
-    rgb = np.array(hls_to_rgb(h, lightness, s)) * 255.
+    rgb = (np.array(hls_to_rgb(h, lightness, s)) * 255).astype(int)
     return RGB(*rgb)