diff --git a/intro.Rmd b/intro.Rmd
index 80f5e0f..2116d36 100644
--- a/intro.Rmd
+++ b/intro.Rmd
@@ -225,6 +225,8 @@ This book isn't just the product of Hadley and Garrett, but is the result of man
 * The \#rstats twitter community who reviewed all of the draft chapters
   and provided tons of useful feedback.
 
+* Tal Galili for augmenting his dendextend package to support a section on clustering that did not make it into the final draft.
+
 This book was written in the open, and many people contributed pull requests to fix minor problems. Special thanks goes to everyone who contributed via GitHub: 
 
 ```{r, results = "asis", echo = FALSE, message = FALSE}