diff --git a/lib/hx509/hx509.h b/lib/hx509/hx509.h
index 1d6139a13..55dd29623 100644
--- a/lib/hx509/hx509.h
+++ b/lib/hx509/hx509.h
@@ -55,6 +55,10 @@ typedef struct hx509_crl *hx509_crl;
 
 typedef void (*hx509_vprint_func)(void *, const char *, va_list);
 
+enum {
+    HX509_VHN_F_ALLOW_NO_MATCH = 1
+};
+
 enum {
     HX509_VALIDATE_F_VALIDATE = 1,
     HX509_VALIDATE_F_VERBOSE = 2