diff --git a/include/wx/mgl/private.h b/include/wx/mgl/private.h
index 5d38d7670b..6b56a9d0b1 100644
--- a/include/wx/mgl/private.h
+++ b/include/wx/mgl/private.h
@@ -17,6 +17,10 @@
 #include <mgraph.hpp>
 #include "pmapi.h"
 
+// the scitech headers define true and false
+#undef true
+#undef false
+
 class WXDLLEXPORT wxBitmap;