diff -Nru m4-1.4.18/debian/changelog m4-1.4.18/debian/changelog
--- m4-1.4.18/debian/changelog	2018-12-01 14:46:54.000000000 +0000
+++ m4-1.4.18/debian/changelog	2019-11-03 12:35:14.000000000 +0000
@@ -1,3 +1,16 @@
+m4 (1.4.18-4) unstable; urgency=medium
+
+  * Move texinfo from Build-Depends-Indep to Build-Depends.
+
+ -- Santiago Vila <sanvila@debian.org>  Sun, 03 Nov 2019 13:35:14 +0100
+
+m4 (1.4.18-3) unstable; urgency=medium
+
+  * Add documentencoding to texi file to fix a FTBFS problem.
+  * Add signature for the upstream tarball.
+
+ -- Santiago Vila <sanvila@debian.org>  Sun, 03 Nov 2019 12:33:42 +0100
+
 m4 (1.4.18-2) unstable; urgency=medium
 
   * Fix FTBFS with glibc 2.28. Closes: #915152.
diff -Nru m4-1.4.18/debian/control m4-1.4.18/debian/control
--- m4-1.4.18/debian/control	2018-12-01 13:00:00.000000000 +0000
+++ m4-1.4.18/debian/control	2019-11-03 11:00:00.000000000 +0000
@@ -3,8 +3,7 @@
 Priority: optional
 Maintainer: Santiago Vila <sanvila@debian.org>
 Standards-Version: 3.9.8
-Build-Depends: debhelper (>= 9.20120311), libsigsegv-dev
-Build-Depends-Indep: texinfo
+Build-Depends: debhelper (>= 9.20120311), libsigsegv-dev, texinfo
 Homepage: http://www.gnu.org/software/m4/
 Rules-Requires-Root: no
 
diff -Nru m4-1.4.18/debian/patches/02-documentencoding.patch m4-1.4.18/debian/patches/02-documentencoding.patch
--- m4-1.4.18/debian/patches/02-documentencoding.patch	1970-01-01 00:00:00.000000000 +0000
+++ m4-1.4.18/debian/patches/02-documentencoding.patch	2019-11-03 11:02:00.000000000 +0000
@@ -0,0 +1,12 @@
+From: Santiago Vila <sanvila@debian.org>
+Subject: Use ISO-8859-1 as documentencoding
+X-Debian-version: 1.4.18-3
+
+--- a/doc/m4.texi
++++ b/doc/m4.texi
+@@ -1,4 +1,5 @@
+ \input texinfo @c -*- texinfo -*-
++@documentencoding ISO-8859-1
+ @comment ========================================================
+ @comment %**start of header
+ @setfilename m4.info
diff -Nru m4-1.4.18/debian/patches/series m4-1.4.18/debian/patches/series
--- m4-1.4.18/debian/patches/series	2018-12-01 13:00:00.000000000 +0000
+++ m4-1.4.18/debian/patches/series	2019-11-03 11:00:00.000000000 +0000
@@ -1 +1,2 @@
 01-fix-ftbfs-with-glibc-2.28.patch
+02-documentencoding.patch