diff --git a/src/vim.h b/src/vim.h
index 05b6632..54a858a 100644
--- a/src/vim.h
+++ b/src/vim.h
@@ -1209,14 +1209,15 @@
 /*
  * arguments for win_split()
  */
-#define WSP_ROOM	1	// require enough room
-#define WSP_VERT	2	// split vertically
-#define WSP_TOP		4	// window at top-left of shell
-#define WSP_BOT		8	// window at bottom-right of shell
-#define WSP_HELP	16	// creating the help window
-#define WSP_BELOW	32	// put new window below/right
-#define WSP_ABOVE	64	// put new window above/left
-#define WSP_NEWLOC	128	// don't copy location list
+#define WSP_ROOM	0x01	// require enough room
+#define WSP_VERT	0x02	// split/equalize vertically
+#define WSP_HOR		0x04	// equalize horizontally
+#define WSP_TOP		0x08	// window at top-left of shell
+#define WSP_BOT		0x10	// window at bottom-right of shell
+#define WSP_HELP	0x20	// creating the help window
+#define WSP_BELOW	0x40	// put new window below/right
+#define WSP_ABOVE	0x80	// put new window above/left
+#define WSP_NEWLOC	0x100	// don't copy location list
 
 /*
  * arguments for gui_set_shellsize()