--- OpenShadingLanguage-Release-1.10.2/src/liboslexec/shadingsys.cpp.orig	2018-12-06 11:41:22.923584600 +0300
+++ OpenShadingLanguage-Release-1.10.2/src/liboslexec/shadingsys.cpp	2018-12-06 11:41:42.863612500 +0300
@@ -54,8 +54,10 @@
 using namespace OSL::pvt;
 
 // avoid naming conflicts with MSVC macros
-#ifdef _MSC_VER
+#ifdef _WIN32
  #undef RGB
+#endif
+#ifdef _MSC_VER
  // We use some of the iso646.h macro names later on in this file. For
  // some compilers (MSVS, I'm looking at you) this is trouble. I don't know
  // how or why that header would have been included here, but it did for at
