diff --git a/quad/quad/scribblings/quad.scrbl b/quad/quad/scribblings/quad.scrbl
index 6221f59e..e1acd9cc 100644
--- a/quad/quad/scribblings/quad.scrbl
+++ b/quad/quad/scribblings/quad.scrbl
@@ -181,7 +181,7 @@ This is the first part of the @tech{Q-expression} that the source file produces
 
 @margin-note{Yes, you can generate your own @tech{Q-expressions} by other means and pass them to @racketmodname[quadwriter] for layout & rendering. See @racket[render-pdf].}
 
-@margin-note{I have no connection to the @link["https://skim-app.sourceforge.io/"]{Skim PDF reader}, but it has an auto-refresh feature that monitors a PDF for changes. This cooperates nicely with Quadwriter during editing sessions: you can have a window on the PDF that updates automatically when you recompile the source file (say, in DrRacket).}
+@margin-note{Mac OS note: I have no connection to the @link["https://skim-app.sourceforge.io/"]{Skim PDF reader}, but it has an auto-refresh feature that monitors a PDF for changes. This cooperates nicely with Quadwriter during editing sessions: you can have a window on the PDF that updates automatically when you recompile the source file (say, in DrRacket).}
 
 @subsection{Quadwriter & markup}