--- src/Makefile.am
+++ src/Makefile.am
@@ -2,7 +2,7 @@
 libname = libonig.la

 AM_CFLAGS = -Wall
-AM_CPPFLAGS = -I$(top_srcdir) -I$(includedir)
+AM_CPPFLAGS = -I$(top_srcdir)

 include_HEADERS = oniguruma.h oniggnu.h onigposix.h
 lib_LTLIBRARIES = $(libname)
