diff --git a/util/mkdef.pl b/util/mkdef.pl
index b62249253..c00cc653a 100755
--- a/util/mkdef.pl
+++ b/util/mkdef.pl
@@ -993,7 +993,7 @@ sub is_valid
 			# EXPORT_VAR_AS_FUNCTION means that global variables
 			# will be represented as functions.  This currently
 			# only happens on VMS-VAX.
-			if ($keyword eq "EXPORT_VAR_AS_FUNCTION" && ($VMSVAX || $W32)) {
+			if ($keyword eq "EXPORT_VAR_AS_FUNCTION" && ($VMSVAX || $W32 || $W16)) {
 				return 1;
 			}
 			return 0;