diff --git a/doc/PKGBUILD.5.txt b/doc/PKGBUILD.5.txt
index af3a388..eeea4da 100644
@@ -273,6 +273,8 @@ variables for use during the build and install process:
This contains the absolute path to the directory where the PKGBUILD is
located, which is usually the output of `$(pwd)` when makepkg is started.
+ `$startdir/src` is not guaranteed to be the same as `$srcdir`, and likewise
+ for `$pkgdir`.
This contains the directory where makepkg extracts, or copies, all source
I'd prefer to add a warning that there is probably no reason to ever use
$startdir in a PKGBUILD rather that mentioning constructs like
$startdir/src which have been deprecated for years now.