diff --git a/Prebuild/src/Core/Parse/Preprocessor.cs b/Prebuild/src/Core/Parse/Preprocessor.cs
index c4e1e61fbe..af21090223 100644
--- a/Prebuild/src/Core/Parse/Preprocessor.cs
+++ b/Prebuild/src/Core/Parse/Preprocessor.cs
@@ -138,6 +138,11 @@ namespace Prebuild.Core.Parse
 				return "Win32";
 			}
 
+            if (File.Exists("/System/Library/Frameworks/Cocoa.framework/Cocoa"))
+            {
+                return "MACOSX";
+            }
+
 			/*
 			 * .NET 1.x, under Mono, the UNIX code is 128. Under
 			 * .NET 2.x, Mono or MS, the UNIX code is 4
diff --git a/bin/Prebuild.exe b/bin/Prebuild.exe
index fce82b99e5..c4bfd4dfa2 100755
Binary files a/bin/Prebuild.exe and b/bin/Prebuild.exe differ