diff --git a/util.hpp b/util.hpp
index 7e1aab6..f9eb0e2 100644
--- a/util.hpp
+++ b/util.hpp
@@ -25,7 +25,7 @@
 
 constexpr auto IPV4_MIN_PREFIX_LENGTH = 1;
 constexpr auto IPV4_MAX_PREFIX_LENGTH = 32;
-constexpr auto IPV6_MAX_PREFIX_LENGTH = 64;
+constexpr auto IPV6_MAX_PREFIX_LENGTH = 128;
 constexpr auto IPV4_PREFIX = "169.254";
 constexpr auto IPV6_PREFIX = "fe80";