diff --git a/Rgbw64Color-object-API.md b/Rgbw64Color-object-API.md
index 4e42e14..a5cc7da 100644
--- a/Rgbw64Color-object-API.md
+++ b/Rgbw64Color-object-API.md
@@ -39,6 +39,10 @@ This will only affect the W color element.
 Construct a Rgbw64Color using RgbColor, converting the R,G,B values and setting W to zero.
 > * _color_ - a RgbColor object.
 
+### Rgbw64Color(Rgb48Color color);
+Construct a Rgbw64Color using Rgb48Color, copying the R,G,B values and setting W to zero.
+> * _color_ - a Rgb48Color object.  
+
 ### Rgbw64Color(RgbwColor color);
 Construct a Rgbw64Color using RgbwColor, converting the R,G,B, and W values.
 > * _color_ - a RgbwColor object.