diff --git a/src/os_mac_conv.c b/src/os_mac_conv.c
index 9d8a6cf..5fdec88 100644
--- a/src/os_mac_conv.c
+++ b/src/os_mac_conv.c
@@ -14,7 +14,7 @@
  */
 
 #define NO_X11_INCLUDES
-#define BalloonEval int   /* used in header files */
+typedef int BalloonEval;    /* used in header files */
 
 #include "vim.h"