diff --git a/README.md b/README.md
index 4efa49c..e0417e6 100644
--- a/README.md
+++ b/README.md
@@ -4,7 +4,12 @@ programming language implementations, and perhaps even as a reference
 for LIBM implementations in OSes.
 
 OpenLIBM builds on Linux and Mac OS X, and with little effort, 
-should build on FreeBSD as well.
+should build on FreeBSD as well. It builds with both, GCC and clang.
 
 The OpenLIBM code derives from the FreeBSD msun implementation, which
 in turn derives from FDLIBM 5.3.
+
+Build instructions:
+
+`make` or `make USEGCC=1` to build with GCC.
+`make USECLANG=1` to build with clang.