diff --git a/css-color-4/Overview.bs b/css-color-4/Overview.bs
index b1560c8779c..7e2642c655d 100644
--- a/css-color-4/Overview.bs
+++ b/css-color-4/Overview.bs
@@ -1293,6 +1293,22 @@ will have a [=powerless=] hue component.
 	have an <em>extremely small</em> chroma rather than precisely ''0%'';
 	as a result, the hue component is [=powerless=].
 
+	When changing a powerless hue component to a [=missing component=],
+	the chroma (or other measure of colorfulness, such as saturation in ''hsl''; see [=analogous components=]) is set to zero
+	to avoid amplifying floating-point noise.
+	Negative values are not clamped to zero,
+	this value is only set to zero when it is larger than zero but smaller or equal to ε.
+	For ''hwb'' follow these steps instead:
+		<pre>
+		1. if W + B is greater than or equal to ε and W + B is less than 100
+			1.1. if W and B are not missing
+				1.1.1. set B to 100 - W
+			1.2. else if W is not missing
+				1.2.1. set W to 100
+			1.3. else if B is not missing
+				1.3.1. set B to 100
+		</pre>
+
 <h3 id=parse-color>
 Parsing a <<color>> Value</h3>