diff --git a/Makefile.am b/Makefile.am
index 6e94dad..00ace29 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -1,6 +1,6 @@
 ACLOCAL_AMFLAGS = -I m4
 
-INCLUDES = $(all_includes) -I$(top_srcdir)/include
+AM_CPPFLAGS = $(all_includes) -I$(top_srcdir)/include
 SUBDIRS = include src
 
 pkgconfigdir = $(libdir)/pkgconfig
diff --git a/src/Makefile.am b/src/Makefile.am
index ce37da5..8a4ca76 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -2,7 +2,7 @@
 # Please read Chapter 6 "Library interface versions" of the libtool documentation before making any modification
 LIBVERSION=0:0:0
 
-INCLUDES = $(all_includes) -I$(top_srcdir)/include
+AM_CPPFLAGS = $(all_includes) -I$(top_srcdir)/include
 AM_CFLAGS = -Wall -ffast-math $(FFTW3F_CFLAGS)
 
 lib_LTLIBRARIES = libosmodsp.la