diff --git a/doc/gitian-building.md b/doc/gitian-building.md
index 5ca8803cf..4525d2817 100755
--- a/doc/gitian-building.md
+++ b/doc/gitian-building.md
@@ -338,6 +338,13 @@ There will be a lot of warnings printed during the build of the image. These can
 
 **Note**: When sudo asks for a password, enter the password for the user *debian* not for *root*.
 
+Special steps to build for Mac OSX
+----------------------------------
+To comppile for the Mac OSX you will need to download the sdk from here:
+https://github.com/phracker/MacOSX-SDKs/releases/download/10.13/MacOSX10.11.sdk.tar.xz
+
+Then it needs to go in the /home/debian/gitian-builder/inputs folder
+
 Getting and building the inputs
 --------------------------------