diff --git a/lib/utils/ip.js b/lib/utils/ip.js
index f39915ee..a7ad24a1 100644
--- a/lib/utils/ip.js
+++ b/lib/utils/ip.js
@@ -280,6 +280,14 @@ IP.parseV6 = function parseV6(str, buf, offset) {
   assert(missing >= 0, 'IPv6 address is too long.');
   assert(parts.length >= 2, 'Not an IPv6 address.');
 
+  for (i = 0; i < parts.length; i++) {
+    word = parts[i];
+    if (IP.isV4Format(word))
+      missing--;
+  }
+
+  assert(missing >= 0, 'IPv6 address is too long.');
+
   for (i = 0; i < parts.length; i++) {
     word = parts[i];