diff --git a/Makefile.am b/Makefile.am
index d7680640..0f381be1 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -1,4 +1,4 @@
-ACLOCAL_AMFLAGS = -I m4
+ACLOCAL_AMFLAGS = -I m4 ${ACLOCAL_FLAGS}
 
 # create default-config.h
 BUILT_SOURCES = default-config.h default-theme.h irssi-version.h