diff --git a/src/option.h b/src/option.h
index 7f70b15..1ed2a4f 100644
--- a/src/option.h
+++ b/src/option.h
@@ -710,6 +710,7 @@
 EXTERN int	p_sta;		/* 'smarttab' */
 #ifdef FEAT_WINDOWS
 EXTERN int	p_sb;		/* 'splitbelow' */
+EXTERN long	p_tpm;		/* 'tabpagemax' */
 # if defined(FEAT_STL_OPT)
 EXTERN char_u	*p_tal;		/* 'tabline' */
 # endif