diff --git a/doc/build.md b/doc/build.md
index 3b2f140cd..21db4a52d 100644
--- a/doc/build.md
+++ b/doc/build.md
@@ -103,6 +103,12 @@ Now, build using the following commands
 cd ..; cp make/config.mk ./config.mk; make -j4
 ```
 
+NOTE:
+If you use OSX El Capitan, brew installs gcc the latest version gcc-6. So you may need to modify Makefile#L46 and change gcc-5 to gcc-6. After that change gcc-5/g++-5 to gcc-6/g++-6 in make/config.mk then build using the following commands
+
+```bash
+cd ..; cp make/config.mk ./config.mk; make -j4
+```
 
 ### Building on Windows
 You need to first clone the xgboost repo with recursive option clone the submodules.
@@ -138,7 +144,7 @@ To build with Visual Studio 2013 use cmake. Make sure you have a recent version
 mkdir build
 cd build
 cmake .. -G"Visual Studio 12 2013 Win64"
-``` 
+```
 
 This specifies an out of source build using the MSVC 12 64 bit generator. Open the .sln file in the build directory and build with Visual Studio. To use the Python module you can copy libxgboost.dll into python-package\xgboost.