diff --git a/src/proto.h b/src/proto.h
index c81212c..5191e75 100644
--- a/src/proto.h
+++ b/src/proto.h
@@ -255,7 +255,7 @@
 # include "if_perlsfio.pro"
 #endif
 
-#if defined(FEAT_MBYTE) && defined(MACOS_X)
+#ifdef MACOS_CONVERT
 # include "os_mac_conv.pro"
 #endif