diff --git a/04-Considering_Safety.md b/04-Considering_Safety.md
index 7136767..f799874 100644
--- a/04-Considering_Safety.md
+++ b/04-Considering_Safety.md
@@ -142,4 +142,4 @@ If you have the possibility to use a compiler that supports C++11, you can use v
 
 ## Additional Resources
 
-[How to Prevent The Next Heartbleed](http://www.dwheeler.com/essays/heartbleed.html) by David Wheeler is a good analysis of the current state of code safety and how to ensure safe code.
+[How to Prevent The Next Heartbleed](https://dwheeler.com/essays/heartbleed.html) by David Wheeler is a good analysis of the current state of code safety and how to ensure safe code.