diff --git a/src/option.h b/src/option.h
index 3818bcd..00374d7 100644
--- a/src/option.h
+++ b/src/option.h
@@ -742,6 +742,14 @@
 EXTERN char_u	*p_su;		/* 'suffixes' */
 EXTERN char_u	*p_sws;		/* 'swapsync' */
 EXTERN char_u	*p_swb;		/* 'switchbuf' */
+EXTERN unsigned	swb_flags;
+#ifdef IN_OPTION_C
+static char *(p_swb_values[]) = {"useopen", "usetab", "split", "newtab", NULL};
+#endif
+#define SWB_USEOPEN		0x001
+#define SWB_USETAB		0x002
+#define SWB_SPLIT		0x004
+#define SWB_NEWTAB		0x008
 EXTERN int	p_tbs;		/* 'tagbsearch' */
 EXTERN long	p_tl;		/* 'taglength' */
 EXTERN int	p_tr;		/* 'tagrelative' */