diff --git a/configure.ac b/configure.ac
index 68e58cd12..aa7c2c21e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -18,15 +18,14 @@
 dnl Catch macros that are not expanded.
 m4_pattern_forbid([^(AX|OLN)_])
 
-AC_PREREQ([2.61])
+AC_PREREQ([2.69])
 
 
 ## ---------------- ##
 ## Package set up.  ##
 ## ---------------- ##
 
-AC_INIT([Olena], [2.1], [olena@lrde.epita.fr], [olena],
-        [http://olena.lrde.epita.fr])
+AC_INIT([Olena],[2.1],[olena@lrde.epita.fr],[olena],[http://olena.lrde.epita.fr])
 
 # M4 macros.
 AC_CONFIG_MACRO_DIR([m4])
@@ -231,8 +230,7 @@ AC_ARG_ENABLE([all],
 ## ------------------ ##
 
 # Use Libtool.
-# To be replaced by a call to LT_INIT as soon as Libtool 2.2 is used.
-AC_PROG_LIBTOOL
+LT_INIT
 
 # Check for Darwin.
 AC_CANONICAL_HOST
diff --git a/m4/oln-with-lib.m4 b/m4/oln-with-lib.m4
index a59acf0ec..7e5b88032 100644
--- a/m4/oln-with-lib.m4
+++ b/m4/oln-with-lib.m4
@@ -77,7 +77,7 @@ AC_DEFUN([OLN_WITH_TESSERACT],
  AC_REQUIRE([AC_PROG_CXX])
  AC_LANG_PUSH([C++])
  AC_ARG_WITH([tesseract],
-   [AC_HELP_STRING([--with-tesseract@<:@=DIR@:>@],
+   [AS_HELP_STRING([--with-tesseract@<:@=DIR@:>@],
      [use $1 (DIR = prefix for TESSERACT installation)])])
  TESSERACT_CPPFLAGS=''
  TESSERACT_LDFLAGS=''
@@ -125,7 +125,7 @@ AC_DEFUN([_OLN_WITH_LIB],
  AC_REQUIRE([AC_PROG_CXX])
  AC_LANG_PUSH([C++])
  AC_ARG_WITH([$4],
-   [AC_HELP_STRING([--with-$4@<:@=DIR@:>@],
+   [AS_HELP_STRING([--with-$4@<:@=DIR@:>@],
      [use $1 (DIR = prefix for $1 installation)])])
  $5_CPPFLAGS=''
  $5_LDFLAGS=''
@@ -177,7 +177,7 @@ AC_DEFUN([_OLN_WITH_LIB_PKG_CONFIG],
  AC_REQUIRE([PKG_PROG_PKG_CONFIG])
  AC_LANG_PUSH([C++])
  AC_ARG_WITH([$4],
-   [AC_HELP_STRING([--with-$4@<:@=DIR@:>@],
+   [AS_HELP_STRING([--with-$4@<:@=DIR@:>@],
      [use $1 (DIR = prefix for $1 installation)])])
  $5_CPPFLAGS=''
  $5_LDFLAGS=''