diff --git a/colour_visuals/planckian_locus.py b/colour_visuals/planckian_locus.py
index 3d845c9..175fefc 100644
--- a/colour_visuals/planckian_locus.py
+++ b/colour_visuals/planckian_locus.py
@@ -303,7 +303,7 @@ def update(self) -> None:
 
             text = gfx.Text(
                 gfx.TextGeometry(
-                    f'{as_int_scalar(label)}{"M" if self._mireds else "K"}',
+                    f"{as_int_scalar(label)}{'M' if self._mireds else 'K'}",
                     font_size=CONSTANTS_COLOUR_STYLE.font.size,
                     screen_space=True,
                     anchor="Bottom-Left",