diff --git a/Configuration.md b/Configuration.md
index e006658..a73e119 100644
--- a/Configuration.md
+++ b/Configuration.md
@@ -105,6 +105,9 @@ background = #fff
 ; Foreground rgba color (e.g. #f00, #ff992a, #ddff1023)
 foreground = #000
 
+; Opacity value between 0.0 and 1.0 used on fade in/out
+dim-value = 1.0
+
 ; Underline size in pixels
 underline-size = 1
 ; Underline rgba color