diff --git a/src/proto/option.pro b/src/proto/option.pro
index 3da74e6..2fe05aa 100644
--- a/src/proto/option.pro
+++ b/src/proto/option.pro
@@ -62,4 +62,5 @@
 long get_sw_value __ARGS((buf_T *buf));
 long get_sts_value __ARGS((void));
 void find_mps_values __ARGS((int *initc, int *findc, int *backwards, int switchit));
+unsigned int get_bkc_value __ARGS((buf_T *buf));
 /* vim: set ft=c : */