diff --git a/doc/Makefile.am b/doc/Makefile.am
index 71ac894..fd7b716 100644
--- a/doc/Makefile.am
+++ b/doc/Makefile.am
@@ -18,6 +18,8 @@
 #  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 ##
 
+.DELETE_ON_ERROR:
+
 path_src   := ../src
 path_tools := ../tools