diff --git a/HISTORY.md b/HISTORY.md
index 1c55720..1a6c4c9 100644
--- a/HISTORY.md
+++ b/HISTORY.md
@@ -1,5 +1,12 @@
 # Sanitize History
 
+## 4.6.6 (2018-07-23)
+
+* Improved performance and memory usage by optimizing `Sanitize#transform_node!`
+  [@stanhu - #183][183]
+
+[183]:https://github.com/rgrove/sanitize/pull/183
+
 ## 4.6.5 (2018-05-16)
 
 * Improved performance slightly by tweaking the order of built-in transformers.
diff --git a/lib/sanitize/version.rb b/lib/sanitize/version.rb
index 89f64e5..5f07021 100644
--- a/lib/sanitize/version.rb
+++ b/lib/sanitize/version.rb
@@ -1,5 +1,5 @@
 # encoding: utf-8
 
 class Sanitize
-  VERSION = '4.6.5'
+  VERSION = '4.6.6'
 end