diff --git a/doc_src/set_color.txt b/doc_src/set_color.txt
index 94e8b8696..ccd2d244c 100644
--- a/doc_src/set_color.txt
+++ b/doc_src/set_color.txt
@@ -9,6 +9,10 @@ Change the foreground and/or background color of the terminal.
 COLOR is one of black, red, green, brown, yellow, blue, magenta,
 purple, cyan, white and normal.
 
+If your terminal supports term256 (modern xterms and OS X Lion),
+you can specify an RGB value with three or six hex digits, such
+as A0FF33 or f2f. fish will choose the closest supported color.
+
 - \c -b, \c --background Set the background color
 - \c -c, \c --print-colors Prints a list of all valid color names
 - \c -h, \c --help Display help message and exit