diff --git a/book.toml b/book.toml
index 7bd3c7f7920..bed3530b7a2 100644
--- a/book.toml
+++ b/book.toml
@@ -23,9 +23,6 @@ class = "bob"
 verbose = false # Report timing information.
 
 # Enable this preprocessor to overlay a large red rectangle on the
-# pages. This will show you an estimate of what the course
-# participants can see during the presentation.
-#
 
 [output.pandoc]
 optional = true