diff --git a/tests/Makefile.am b/tests/Makefile.am
index 74495455..767919e9 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -27,7 +27,7 @@ os_wrappers_test_SOURCES = 			\
 	../src/wayland-os.c			\
 	$(test_runner_src)
 
-AM_CFLAGS = $(GCC_CFLAGS) $(FFI_CFLAGS)
+AM_CFLAGS = $(GCC_CFLAGS) $(FFI_CFLAGS) -I../src
 LDADD = $(top_builddir)/src/libwayland-util.la \
 	$(top_builddir)/src/libwayland-server.la \
 	-lrt -ldl $(FFI_LIBS)