diff --git a/documentation/content/en/books/porters-handbook/slow-porting/_index.adoc b/documentation/content/en/books/porters-handbook/slow-porting/_index.adoc
--- a/documentation/content/en/books/porters-handbook/slow-porting/_index.adoc
+++ b/documentation/content/en/books/porters-handbook/slow-porting/_index.adoc
@@ -332,7 +332,7 @@
 ....
 % ls -l files/foo-patches
 -rw-r--r--  1 root  wheel    350 Jan 16 01:27 patch-Makefile.in
--rw-r--r--  1 root  wheel   3084 Jan 18 15:37 patch-configure
+-rw-r--r--  1 root  wheel   3084 Jan 18 15:37 patch-configure.ac
 ....
 
 Then add this to the [.filename]#Makefile#: