diff --git a/src/racket/include/scheme.h b/src/racket/include/scheme.h
index 560f0dfc07..ecd916cd4b 100644
--- a/src/racket/include/scheme.h
+++ b/src/racket/include/scheme.h
@@ -110,6 +110,9 @@ typedef long FILE;
 #ifndef MSC_IZE
 # define MSC_IZE(x) x
 #endif
+#ifndef M_MSC_IZE
+# define M_MSC_IZE(x) x
+#endif
 #ifndef MSCBOR_IZE
 # define MSCBOR_IZE(x) MSC_IZE(x)
 #endif