diff --git a/book/02-git-basics/sections/recording-changes.asc b/book/02-git-basics/sections/recording-changes.asc
index c750d889a..9ca266370 100644
--- a/book/02-git-basics/sections/recording-changes.asc
+++ b/book/02-git-basics/sections/recording-changes.asc
@@ -246,7 +246,7 @@ build/
 # ignore doc/notes.txt, but not doc/server/arch.txt
 doc/*.txt
 
-# ignore all .pdf files in the doc/ directory
+# ignore all .pdf files in the doc/ directory and any of its subdirectories
 doc/**/*.pdf
 ----