Index: configure.ac
===================================================================
--- configure.ac	(revision 191433)
+++ configure.ac	(working copy)
@@ -37,6 +37,8 @@ AC_CONFIG_HEADER(config.h)
 AC_CANONICAL_SYSTEM
 target_alias=${target_alias-$host_alias}
 
+AC_USE_SYSTEM_EXTENSIONS
+
 libtool_VERSION=1:0:0
 AC_SUBST(libtool_VERSION)
 
Index: mmapio.c
===================================================================
--- mmapio.c	(revision 191432)
+++ mmapio.c	(working copy)
@@ -30,8 +30,6 @@ STRICT LIABILITY, OR TORT (INCLUDING NEG
 IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 POSSIBILITY OF SUCH DAMAGE.  */
 
-#define _GNU_SOURCE
-
 #include "config.h"
 
 #include <errno.h>