diff --git a/src/charset.c b/src/charset.c
index 399f258..e02f719 100644
--- a/src/charset.c
+++ b/src/charset.c
@@ -739,8 +739,8 @@
     RET_WIN_BUF_CHARTABSIZE(curwin, curbuf, p, col)
 }
 
-#ifdef FEAT_LINEBREAK
-    static int
+#if defined(FEAT_LINEBREAK) || defined(PROTO)
+    int
 win_chartabsize(win_T *wp, char_u *p, colnr_T col)
 {
     RET_WIN_BUF_CHARTABSIZE(wp, wp->w_buffer, p, col)