diff --git a/src/proto/tabpanel.pro b/src/proto/tabpanel.pro
index 34c3e52..617f802 100644
--- a/src/proto/tabpanel.pro
+++ b/src/proto/tabpanel.pro
@@ -1,6 +1,6 @@
 /* tabpanel.c */
 int tabpanel_width(void);
-int tabpanel_leftcol(win_T *wp);
+int tabpanel_leftcol(void);
 int tabpanelopt_changed(void);
 void draw_tabpanel(void);
 int get_tabpagenr_on_tabpanel(void);