diff --git a/core/src/main/java/org/elasticsearch/common/LegacyTimeBasedUUIDGenerator.java b/core/src/main/java/org/elasticsearch/common/LegacyTimeBasedUUIDGenerator.java
index 2bf19f1dcbb..74a08711042 100644
--- a/core/src/main/java/org/elasticsearch/common/LegacyTimeBasedUUIDGenerator.java
+++ b/core/src/main/java/org/elasticsearch/common/LegacyTimeBasedUUIDGenerator.java
@@ -23,8 +23,9 @@ import java.util.Base64;
 import java.util.concurrent.atomic.AtomicInteger;
 
 /**
- * These are essentially flake ids (http://boundary.com/blog/2012/01/12/flake-a-decentralized-k-ordered-unique-id-generator-in-erlang) but
- * we use 6 (not 8) bytes for timestamp, and use 3 (not 2) bytes for sequence number.
+ * These are essentially flake ids, but we use 6 (not 8) bytes for timestamp, and use 3 (not 2) bytes for sequence number.
+ * For more information about flake ids, check out
+ * https://archive.fo/2015.07.08-082503/http://www.boundary.com/blog/2012/01/flake-a-decentralized-k-ordered-unique-id-generator-in-erlang/
  */
 
 class LegacyTimeBasedUUIDGenerator implements UUIDGenerator {
diff --git a/core/src/main/java/org/elasticsearch/common/TimeBasedUUIDGenerator.java b/core/src/main/java/org/elasticsearch/common/TimeBasedUUIDGenerator.java
index 550559eac9f..c30a8d0aaa2 100644
--- a/core/src/main/java/org/elasticsearch/common/TimeBasedUUIDGenerator.java
+++ b/core/src/main/java/org/elasticsearch/common/TimeBasedUUIDGenerator.java
@@ -22,9 +22,13 @@ package org.elasticsearch.common;
 import java.util.Base64;
 import java.util.concurrent.atomic.AtomicInteger;
 
-/** These are essentially flake ids (http://boundary.com/blog/2012/01/12/flake-a-decentralized-k-ordered-unique-id-generator-in-erlang) but
- *  we use 6 (not 8) bytes for timestamp, and use 3 (not 2) bytes for sequence number. We also reorder bytes in a way that does not make ids
- *  sort in order anymore, but is more friendly to the way that the Lucene terms dictionary is structured. */
+/**
+ * These are essentially flake ids but we use 6 (not 8) bytes for timestamp, and use 3 (not 2) bytes for sequence number. We also reorder
+ * bytes in a way that does not make ids sort in order anymore, but is more friendly to the way that the Lucene terms dictionary is
+ * structured.
+ * For more information about flake ids, check out
+ * https://archive.fo/2015.07.08-082503/http://www.boundary.com/blog/2012/01/flake-a-decentralized-k-ordered-unique-id-generator-in-erlang/
+ */
 
 class TimeBasedUUIDGenerator implements UUIDGenerator {