diff --git a/src/chinadns.c b/src/chinadns.c
index 6716554..4674f67 100644
--- a/src/chinadns.c
+++ b/src/chinadns.c
@@ -797,13 +797,19 @@ static int should_filter_query(ns_msg msg, struct in_addr dns_addr) {
           if (bidirectional) {
             // filter DNS result from foreign dns if result is inside chn
             return 1;
+          } else {
+            return -1;
           }
+        } else {
+          return 0;
         }
       } else {
         // result is foreign
         if (dns_is_chn) {
           // filter DNS result from chn dns if result is outside chn
           return 1;
+        } else {
+          return -1;
         }
       }
     } else if (type == ns_t_aaaa || type == ns_t_ptr) {