diff --git a/src/os_macosx.m b/src/os_macosx.m
index d5d0cfe1e2..af3d275e7c 100644
--- a/src/os_macosx.m
+++ b/src/os_macosx.m
@@ -15,10 +15,12 @@
     Error: MACOS 9 is no longer supported in Vim 7
 #endif
 
+#ifndef FEAT_GUI_MACVIM
 /* Avoid a conflict for the definition of Boolean between Mac header files and
  * X11 header files. */
-#define NO_X11_INCLUDES
-#define BalloonEval int   /* used in header files */
+# define NO_X11_INCLUDES
+# define BalloonEval int   /* used in header files */
+#endif
 
 #include "vim.h"
 #import <Cocoa/Cocoa.h>