diff --git a/README.md b/README.md
index d33aabc..bfa1783 100644
--- a/README.md
+++ b/README.md
@@ -3,7 +3,7 @@ Pollen: the book is a program
 
 A book-publishing system written in [Racket](http://racket-lang.org). Unstable. Incomplete. Et cetera. It’s becoming more civilized. But this is the actual software I use to publish & maintain my web-based book [Butterick's Practical Typography](http://practicaltypography.com).
 
-Install from the command line like so:
+Using Racket 6.0+, install from the command line like so:
 
     raco pkg install pollen