diff --git a/Makefile.am b/Makefile.am
index 9bcba6d..0129c2b 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -1,3 +1,5 @@
+ACLOCAL_AMFLAGS = -Im4
+
 if WANT_LIBSDBUSPLUS
 
 nobase_include_HEADERS = \