diff --git a/_posts/13-04-01-Books.md b/_posts/13-04-01-Books.md
index 2de5f79..5282009 100644
--- a/_posts/13-04-01-Books.md
+++ b/_posts/13-04-01-Books.md
@@ -24,6 +24,6 @@ available as a book completely for free
 your code under control in a series of small, specific steps
 * [Building Secure PHP Apps](https://leanpub.com/buildingsecurephpapps) - Learn the security basics that a senior developer usually acquires over years of experience, all condensed down into one quick and easy handbook
 * [The Grumpy Programmer's Guide To Building Testable PHP Applications](https://leanpub.com/grumpy-testing) - Learning to write testable doesn't have to suck
-* [Build APIs You Won't Hate](https://leanpub.com/build-apis-you-wont-hate) - Everyone and their dog wants an API, so you should probably learn how to build them
+* [Securing PHP: Core Concepts](https://leanpub.com/securingphp-coreconcepts) - A guide to some of the most common security terms and provides some examples of them in every day PHP
 * [Scaling PHP](https://leanpub.com/scalingphp) - Stop playing sysadmin and get back to coding
 * [Signaling PHP](https://leanpub.com/signalingphp) - PCNLT signals are a great help when writing PHP scripts that run from the command line.