diff --git a/README.md b/README.md
index aea49d9..1a02fb9 100644
--- a/README.md
+++ b/README.md
@@ -13,6 +13,7 @@ git submodule init
 git submodule update
 ```
 
-Then use the Makefile to build the paper.
+Then use the Makefile to build the paper. One R library that we use to paralleize the code, `Rmpi`, assumes either that you are using our local linux cluster (keeling) or you have installed the openmpi libraries via `brew install openmpi` on an OS X machine. We hope that the R package, `Rmpi`, becomes less system dependent to install in the future. 
 
-Some of the simulations take a very long time (more than 24 hours) on a cluster with 36 cores. We save the products of these runs in a Dropbox directory.
+Some of the simulations take a very long time (more than 24 hours) on a cluster
+with 36 cores. We save the products of these runs in a Dropbox directory.