diff --git a/src/charon/plugins/ha_sync/Makefile.am b/src/charon/plugins/ha_sync/Makefile.am
index 15f409699..aadf7dd65 100644
--- a/src/charon/plugins/ha_sync/Makefile.am
+++ b/src/charon/plugins/ha_sync/Makefile.am
@@ -1,5 +1,5 @@
 
-INCLUDES = -I${linuxdir} -I$(top_srcdir)/src/libstrongswan -I$(top_srcdir)/src/charon
+INCLUDES = -I${linux_headers} -I$(top_srcdir)/src/libstrongswan -I$(top_srcdir)/src/charon
 
 AM_CFLAGS = -rdynamic -DIPSEC_PIDDIR=\"${piddir}\"