diff --git a/en_US.ISO8859-1/books/porters-handbook/book.sgml b/en_US.ISO8859-1/books/porters-handbook/book.sgml
index 10ae5c82b0..93c6c8db8e 100644
--- a/en_US.ISO8859-1/books/porters-handbook/book.sgml
+++ b/en_US.ISO8859-1/books/porters-handbook/book.sgml
@@ -3825,12 +3825,20 @@ ${PREFIX}/man/ja/man4/baz.4.gz</programlisting>
 	      the inclusion of <filename>bsd.port.pre.mk</filename>.
 	      The <makevar>WITH_*</makevar> and <makevar>WITHOUT_*</makevar>
 	      variables can only be tested after the inclusion of
-	      <filename>bsd.port.pre.mk</filename>.  Due to a deficiency
-	      in the infrastructure, you can only test
-	      <makevar>WITH_*</makevar> variables for options, which are
+	      <filename>bsd.port.pre.mk</filename>.</para>
+
+	    <para>
+	      Due to a deficiency in the infrastructure, you can only test
+	      <makevar>WITH_*</makevar> variables for options which are
 	      <literal>OFF</literal> by default, and
-	      <makevar>WITHOUT_*</makevar> variables for options, which
-	      defaults to <literal>ON</literal>.</para>
+	      <makevar>WITHOUT_*</makevar> variables for options which
+	      default to <literal>ON</literal>.  The reasoning behind this:
+	      when packages are built with <makevar>PACKAGE_BUILDING</makevar> or
+	      <makevar>BATCH</makevar> defined, the <command>config</command>
+	      target is not run, and therefore no <makevar>OPTIONS</makevar>
+	      are selected.  This would cause <command>make depends</command> and
+	      <command>make describe</command> to break for ports not following
+	      the aforementioned rule.</para>
 
 	<sect3>
 	  <title>Example</title>