diff --git a/README.md b/README.md
index fb0376a..2a27e09 100644
--- a/README.md
+++ b/README.md
@@ -5,4 +5,4 @@ C++ GameDev related math helpers.  These helpers will be designed for ease of us
 
 Requirements
 -----------
-Aside from a C++ compiler, there are no external dependencies outside of the stdlib. 
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+Aside from a C++ compiler, there are no external dependencies outside of the stdlib.  However, for running unit tests this uses `[igloo](https://github.com/joakimkarlsson/igloo)`, already referenced as an external. 
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