diff --git a/Makefile.am b/Makefile.am
index 5df5a55..13eefe0 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -1,3 +1,4 @@
+ACLOCAL_AMFLAGS = -I m4
 MAINTAINERCLEANFILES = Makefile.in forecasts.edj
 
 SUBDIRS = images po