diff --git a/configure.in b/configure.in
index 558a58611..d8b4fd0e7 100644
--- a/configure.in
+++ b/configure.in
@@ -27,6 +27,7 @@ AM_INIT_AUTOMAKE([weechat], [0.2.1-cvs])
 # Checks for programs
 AC_PROG_CC
 AC_PROG_MAKE_SET
+AC_GNU_SOURCE
 AM_PROG_LIBTOOL
 
 # Add some flags for some OS
diff --git a/weechat/configure.in b/weechat/configure.in
index 558a58611..d8b4fd0e7 100644
--- a/weechat/configure.in
+++ b/weechat/configure.in
@@ -27,6 +27,7 @@ AM_INIT_AUTOMAKE([weechat], [0.2.1-cvs])
 # Checks for programs
 AC_PROG_CC
 AC_PROG_MAKE_SET
+AC_GNU_SOURCE
 AM_PROG_LIBTOOL
 
 # Add some flags for some OS