diff --git a/README.md b/README.md
index 521695662..983e0d0cc 100644
--- a/README.md
+++ b/README.md
@@ -34,6 +34,7 @@ Install OpenCV using
 
 And install OpenGV using
 
+    brew install eigen
     git clone https://github.com/paulinus/opengv.git
     cd opengv
     mkdir build