diff --git a/src/proto/channel.pro b/src/proto/channel.pro
index a263c1c..d14337d 100644
--- a/src/proto/channel.pro
+++ b/src/proto/channel.pro
@@ -48,7 +48,7 @@
 void clear_job_options(jobopt_T *opt);
 void free_job_options(jobopt_T *opt);
 int get_job_options(typval_T *tv, jobopt_T *opt, int supported);
-channel_T *get_channel_arg(typval_T *tv, int check_open);
+channel_T *get_channel_arg(typval_T *tv, int check_open, int reading, int part);
 void job_unref(job_T *job);
 int free_unused_jobs_contents(int copyID, int mask);
 void free_unused_jobs(int copyID, int mask);