diff --git a/src/vim.h b/src/vim.h
index 4b41857..df396ec 100644
--- a/src/vim.h
+++ b/src/vim.h
@@ -2154,8 +2154,9 @@
 # define number_width(x) 7
 #endif
 
-/* This must come after including proto.h */
-#if !(defined(FEAT_MBYTE) && defined(WIN3264))
+/* This must come after including proto.h.
+ * For VMS this is defined in macros.h. */
+#if !(defined(FEAT_MBYTE) && defined(WIN3264)) && !defined(VMS)
 # define mch_open(n, m, p)	open((n), (m), (p))
 # define mch_fopen(n, p)	fopen((n), (p))
 #endif