diff --git a/Makefile.am b/Makefile.am
index 46c9106..ed35f73 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -1,5 +1,5 @@
 ## Process this file with automake to produce Makefile.in
-ACLOCAL_AMFLAGS = -I m4
+ACLOCAL_AMFLAGS = -I m4 ${ACLOCAL_FLAGS}
 
 SUBDIRS = pluma pixmaps po data plugin-loaders plugins docs tests win32 osx