diff --git a/css-color-4/Overview.bs b/css-color-4/Overview.bs
index 411966f7add..1a995e7ffbb 100644
--- a/css-color-4/Overview.bs
+++ b/css-color-4/Overview.bs
@@ -4939,12 +4939,15 @@ Deviations from Perceptual Uniformity: Hue Curvature
CSS Gamut Mapping to an RGB Destination
- This CSS gamut mapping algorithm
+ The CSS gamut mapping algorithm
applies to individual,
Standard Dynamic Range (SDR) CSS colors
which are out of gamut
of an RGB display
and thus require to be css gamut mapped.
+ It also applies to colors being converted
+ to HSL or HWB, which cannot express
+ colors outside the sRGB gamut.
It implements a relative colorimetric intent,
and colors inside the destination gamut are unchanged.