diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
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--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -19,6 +19,7 @@ Before you file an issue or a pull request, read the following tips on how to ke
 
 ### Prerequisites for developing Kitematic on Mac 
 You will need to install: 
+- The [Docker Toolbox](https://docker.com/toolbox)
 -  [Node.js 0.10.38](https://nodejs.org/dist/v0.10.38/)
 - The latest Xcode from the Apple App Store.