--- a/libutil/tests/Makefile.am
+++ b/libutil/tests/Makefile.am
@@ -1,5 +1,5 @@
 AM_CPPFLAGS = \
-	-I ${top_srcdir}/libutil
+	-I ${top_srcdir}/libutil @OP_CPPFLAGS@
 
 AM_CFLAGS = @OP_CFLAGS@