diff --git a/servo/README.md b/servo/README.md
index 8a0504b1d168..69ca7a3b9ddf 100644
--- a/servo/README.md
+++ b/servo/README.md
@@ -25,7 +25,7 @@ On OS X (MacPorts):
 sudo port install python27 py27-virtualenv cmake
 ```
 
-On OS X 10.11, you also have to install openssl:
+On OS X 10.11 (El Capitan), you also have to install openssl:
 
 ``` sh
 brew install openssl