diff --git a/configure.ac b/configure.ac
index cb4eb2a..9c31cc8 100644
--- a/configure.ac
+++ b/configure.ac
@@ -3,7 +3,7 @@ dnl configure.ac -- Process this file with autoconf to produce a configure scrip
 AC_INIT([petidomo], m4_esyscmd([build-aux/git-version-gen .tarball-version]), [simons@cryp.to], [petidomo], [http://petidomo.sourceforge.net/])
 AC_CONFIG_SRCDIR([petidomo.h])
 AC_CONFIG_AUX_DIR([build-aux])
-AM_INIT_AUTOMAKE([1.11 -Wall gnu])
+AM_INIT_AUTOMAKE([1.11 -Wall gnu subdir-objects])
 AC_CONFIG_MACRO_DIR([build-aux])
 
 AC_COPYRIGHT([dnl