--- a/lib/Makefile.am	Fri Mar 03 17:08:39 2017 +0100
+++ b/lib/Makefile.am	Fri Aug 18 12:30:16 2017 +0200
@@ -50,7 +50,7 @@
 	slave_config.h \
 	voe_handler.h
 
-libethercat_la_CFLAGS = -fno-strict-aliasing -Wall
+libethercat_la_CFLAGS = -fno-strict-aliasing -Wall -I$(top_srcdir)
 libethercat_la_LDFLAGS = -version-info 1:0:0
 
 #------------------------------------------------------------------------------