diff --git a/configure.ac b/configure.ac
index 49689fb01..f4e54ea6b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1,5 +1,5 @@
 dnl Configuration for the toplevel directory of GNU gettext
-dnl Copyright (C) 1995-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 1995-2020 Free Software Foundation, Inc.
 dnl
 dnl This program is free software: you can redistribute it and/or modify
 dnl it under the terms of the GNU General Public License as published by
@@ -16,7 +16,7 @@ dnl along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 dnl Process this file with autoconf to produce a configure script.
 
-AC_PREREQ([2.63])
+AC_PREREQ([2.64])
 AC_INIT([gettext],
 	m4_esyscmd([build-aux/git-version-gen .tarball-version]),
 	[bug-gettext@gnu.org])
diff --git a/gettext-runtime/configure.ac b/gettext-runtime/configure.ac
index b2bfda5e1..93f24054e 100644
--- a/gettext-runtime/configure.ac
+++ b/gettext-runtime/configure.ac
@@ -16,7 +16,7 @@ dnl along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 dnl Process this file with autoconf to produce a configure script.
 
-AC_PREREQ([2.63])
+AC_PREREQ([2.64])
 AC_INIT([gettext-runtime],
 	m4_esyscmd([../build-aux/git-version-gen ../.tarball-version]),
 	[bug-gettext@gnu.org])
diff --git a/gettext-runtime/libasprintf/configure.ac b/gettext-runtime/libasprintf/configure.ac
index 776a1f4d7..5ebfc17e5 100644
--- a/gettext-runtime/libasprintf/configure.ac
+++ b/gettext-runtime/libasprintf/configure.ac
@@ -1,5 +1,5 @@
 dnl Configuration for the GNU libasprintf library
-dnl Copyright (C) 2002-2012, 2016, 2018-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2002-2012, 2016, 2018-2020 Free Software Foundation, Inc.
 dnl
 dnl This program is free software: you can redistribute it and/or modify
 dnl it under the terms of the GNU General Public License as published by
@@ -16,7 +16,7 @@ dnl along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 dnl Process this file with autoconf to produce a configure script.
 
-AC_PREREQ([2.63])
+AC_PREREQ([2.64])
 AC_INIT([libasprintf], [1.0])
 AC_CONFIG_SRCDIR([vasprintf.c])
 AC_CONFIG_AUX_DIR([../../build-aux])
diff --git a/gettext-tools/configure.ac b/gettext-tools/configure.ac
index 04db78149..c4c3eedcc 100644
--- a/gettext-tools/configure.ac
+++ b/gettext-tools/configure.ac
@@ -16,7 +16,7 @@ dnl along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 dnl Process this file with autoconf to produce a configure script.
 
-AC_PREREQ([2.63])
+AC_PREREQ([2.64])
 AC_INIT([gettext-tools],
 	m4_esyscmd([../build-aux/git-version-gen ../.tarball-version]),
 	[bug-gettext@gnu.org])
diff --git a/gettext-tools/examples/configure.ac b/gettext-tools/examples/configure.ac
index b25e72a44..249fd14cd 100644
--- a/gettext-tools/examples/configure.ac
+++ b/gettext-tools/examples/configure.ac
@@ -1,5 +1,5 @@
 dnl Configuration for the gettext-tools/examples directory of GNU gettext
-dnl Copyright (C) 2006, 2009, 2014, 2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2006, 2009, 2014, 2019-2020 Free Software Foundation, Inc.
 dnl
 dnl This program is free software: you can redistribute it and/or modify
 dnl it under the terms of the GNU General Public License as published by
@@ -16,7 +16,7 @@ dnl along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 dnl Process this file with autoconf to produce a configure script.
 
-AC_PREREQ([2.57])
+AC_PREREQ([2.64])
 AC_INIT([gettext-examples],
 	m4_esyscmd([../../build-aux/git-version-gen ../../.tarball-version]),
 	[bug-gettext@gnu.org])
diff --git a/libtextstyle/.gitignore b/libtextstyle/.gitignore
index 509a54296..a2e030de9 100644
--- a/libtextstyle/.gitignore
+++ b/libtextstyle/.gitignore
@@ -197,6 +197,7 @@
 /lib/term-styled-ostream.oo.c
 /lib/term-styled-ostream.oo.h
 /lib/terminfo.h
+/lib/thread-optim.h
 /lib/time.in.h
 /lib/tparm.c
 /lib/tputs.c
diff --git a/libtextstyle/configure.ac b/libtextstyle/configure.ac
index 63b4c2a1e..8d424eeb7 100644
--- a/libtextstyle/configure.ac
+++ b/libtextstyle/configure.ac
@@ -1,5 +1,5 @@
 dnl Configuration for the toplevel directory of GNU libtextstyle
-dnl Copyright (C) 2009-2019 Free Software Foundation, Inc.
+dnl Copyright (C) 2009-2020 Free Software Foundation, Inc.
 dnl
 dnl This program is free software: you can redistribute it and/or modify
 dnl it under the terms of the GNU General Public License as published by
@@ -16,7 +16,7 @@ dnl along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 dnl Process this file with autoconf to produce a configure script.
 
-AC_PREREQ([2.63])
+AC_PREREQ([2.64])
 AC_INIT
 AC_CONFIG_SRCDIR([version.sh])
 AC_CONFIG_AUX_DIR([build-aux])