diff --git a/docs/dht_sec.rst b/docs/dht_sec.rst
index b571a8df9..883164b61 100644
--- a/docs/dht_sec.rst
+++ b/docs/dht_sec.rst
@@ -95,7 +95,7 @@ Example code code for calculating a valid node ID::
 	int mod_shift = 6 * 4 / num_octets; // 6 or 3, depending on IPv4 and IPv6
 	while (num_octets)
 	{
-		seed = (uint64_t(seed) * ip[num_octets]) & (modulus-1);
+		seed = (uint64_t(seed) * ip[num_octets-1]) & (modulus-1);
 		modulus <<= mod_shift;
 		--num_octets;
 	}
@@ -119,7 +119,7 @@ Example code to verify a node ID::
 	int mod_shift = 6 * 4 / num_octets; // 6 or 3, depending on IPv4 and IPv6
 	while (num_octets)
 	{
-		seed = (uint64_t(seed) * ip[num_octets]) & (modulus-1);
+		seed = (uint64_t(seed) * ip[num_octets-1]) & (modulus-1);
 		modulus <<= mod_shift;
 		--num_octets;
 	}
diff --git a/src/kademlia/node_id.cpp b/src/kademlia/node_id.cpp
index a26a4bf27..4ba830b6b 100644
--- a/src/kademlia/node_id.cpp
+++ b/src/kademlia/node_id.cpp
@@ -127,7 +127,7 @@ node_id generate_id_impl(address const& ip, boost::uint32_t r)
 
 	while (num_octets)
 	{
-		seed *= p[num_octets];
+		seed *= p[num_octets-1];
 		seed &= (modulus-1);
 		modulus <<= mod_shift;
 		--num_octets;