diff --git a/src/kademlia/node_id.cpp b/src/kademlia/node_id.cpp
index 92ef04d22..1be063ade 100644
--- a/src/kademlia/node_id.cpp
+++ b/src/kademlia/node_id.cpp
@@ -104,8 +104,8 @@ node_id generate_id_impl(address const& ip_, boost::uint32_t r)
 {
 	boost::uint8_t* ip = 0;
 	
-	const static boost::uint8_t v4mask[] = { 0x01, 0x07, 0x1f, 0x7f };
-	const static boost::uint8_t v6mask[] = { 0x00, 0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f, 0x7f };
+	const static boost::uint8_t v4mask[] = { 0x03, 0x0f, 0x3f, 0xff };
+	const static boost::uint8_t v6mask[] = { 0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f, 0x7f, 0xff };
 	boost::uint8_t const* mask = 0;
 	int num_octets = 0;
 
@@ -141,10 +141,9 @@ node_id generate_id_impl(address const& ip_, boost::uint32_t r)
 
 	id[0] = (c >> 24) & 0xff;
 	id[1] = (c >> 16) & 0xff;
-	id[2] = (c >> 8) & 0xff;
-	id[3] = c & 0xff;
+	id[2] = ((c >> 8) & 0xf8) | (random() & 0x7);
 
-	for (int i = 4; i < 19; ++i) id[i] = random();
+	for (int i = 3; i < 19; ++i) id[i] = random();
 	id[19] = r;
 
 	return id;
@@ -166,7 +165,7 @@ bool verify_id(node_id const& nid, address const& source_ip)
 	if (is_local(source_ip)) return true;
 
 	node_id h = generate_id_impl(source_ip, nid[19]);
-	return memcmp(&nid[0], &h[0], 4) == 0;
+	return nid[0] == h[0] && nid[1] == h[1] && (nid[2] & 0xf8) == (h[2] & 0xf8);
 }
 
 node_id generate_id(address const& ip)
diff --git a/test/test_dht.cpp b/test/test_dht.cpp
index 784ab44cd..b4c97faba 100644
--- a/test/test_dht.cpp
+++ b/test/test_dht.cpp
@@ -629,7 +629,7 @@ int test_main()
 	// this is one of the test vectors from:
 	// http://libtorrent.org/dht_sec.html
 	source = udp::endpoint(address::from_string("124.31.75.21"), 20);
-	node_id nid = to_hash("1712f6c70c5d6a4ec8a88e4c6ab4c28b95eee401");
+	node_id nid = to_hash("d2a6dfc70c5d6a4ec8a88e4c6ab4c28b95eee401");
 	send_dht_request(node, "find_node", source, &response, "10", 0, 0, std::string()
 		, 0, "0101010101010101010101010101010101010101", 0, false, false, std::string(), std::string(), -1, 0, &nid);
 
@@ -1344,21 +1344,23 @@ int test_main()
 
 		int rs[] = { 1,86,22,65,90 };
 
-		boost::uint8_t prefixes[][4] =
+		boost::uint8_t prefixes[][3] =
 		{
-			{ 0x17, 0x12, 0xf6, 0xc7 },
-			{ 0x94, 0x64, 0x06, 0xc1 },
-			{ 0xfe, 0xfd, 0x92, 0x20 },
-			{ 0xaf, 0x15, 0x46, 0xdd },
-			{ 0xa9, 0xe9, 0x20, 0xbf }
+			{ 0xd2, 0xa6, 0xdf },
+			{ 0x51, 0xd0, 0x29 },
+			{ 0xfd, 0x33, 0x4a },
+			{ 0x6a, 0xa1, 0x69 },
+			{ 0xeb, 0x64, 0x34 }
 		};
 
 		for (int i = 0; i < 5; ++i)
 		{
 			address a = address_v4::from_string(ips[i]);
 			node_id id = generate_id_impl(a, rs[i]);
-			for (int j = 0; j < 4; ++j)
-				TEST_CHECK(id[j] == prefixes[i][j]);
+			TEST_CHECK(id[0] == prefixes[i][0]);
+			TEST_CHECK(id[1] == prefixes[i][1]);
+			TEST_CHECK((id[2] & 0xf8) == (prefixes[i][2] & 0xf8));
+
 			TEST_CHECK(id[19] == rs[i]);
 			fprintf(stderr, "IP address: %s r: %d node ID: %s\n", ips[i]
 				, rs[i], to_hex(id.to_string()).c_str());