diff --git a/src/core/ngx_resolver.c b/src/core/ngx_resolver.c
index 9b13172..12dab09 100644
--- a/src/core/ngx_resolver.c
+++ b/src/core/ngx_resolver.c
@@ -3958,6 +3958,11 @@
         }
 
         if (n & 0xc0) {
+            if ((n & 0xc0) != 0xc0) {
+                err = "invalid label type in DNS response";
+                goto invalid;
+            }
+
             if (p >= last) {
                 err = "name is out of DNS response";
                 goto invalid;