diff --git a/Compat/Compat.cs b/Compat/Compat.cs
index 51dcce6..fbb6434 100644
--- a/Compat/Compat.cs
+++ b/Compat/Compat.cs
@@ -63,7 +63,11 @@ public delegate int diagnostics_Function(IntPtr face_handle, int messcode, strin
         private RasterInterf ()
         {
             PlatformID pid = Environment.OSVersion.Platform;
+#if __MonoCS__
             if ( pid != PlatformID.Unix && pid != PlatformID.MacOSX )
+#else
+            if ( pid != PlatformID.Unix )
+#endif
             {
                 string path = Path.GetDirectoryName(Assembly.GetEntryAssembly().Location);
                 path = Path.Combine(path, IntPtr.Size == 8 ? "Win64" : "Win32");