diff --git a/Makefile.am b/Makefile.am
index 663e85e..dc13961 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -7,7 +7,7 @@
 ## Additional flags to pass to aclocal when it is invoked automatically at
 ## make time. The ${ACLOCAL_FLAGS} variable is picked up from the environment
 ## to provide a way for the user to supply additional arguments.
-ACLOCAL_AMFLAGS = ${ACLOCAL_FLAGS}
+ACLOCAL_AMFLAGS = ${ACLOCAL_FLAGS} -I m4
 
 lib_LTLIBRARIES = libndn-c.la libndn-cpp.la