diff --git a/src/channel.c b/src/channel.c
index 8b0abdc..a023c9f 100644
--- a/src/channel.c
+++ b/src/channel.c
@@ -55,6 +55,14 @@
 #endif
 
 static void channel_read(channel_T *channel, ch_part_T part, char *func);
+# if defined(MSWIN) || defined(FEAT_GUI_X11) || defined(FEAT_GUI_GTK)
+static channel_T *channel_fd2channel(sock_T fd, ch_part_T *partp);
+# endif
+static ch_mode_T channel_get_mode(channel_T *channel, ch_part_T part);
+static int channel_get_timeout(channel_T *channel, ch_part_T part);
+static ch_part_T channel_part_send(channel_T *channel);
+static ch_part_T channel_part_read(channel_T *channel);
+static void free_job_options(jobopt_T *opt);
 
 /* Whether a redraw is needed for appending a line to a buffer. */
 static int channel_need_redraw = FALSE;
@@ -1175,7 +1183,7 @@
 /*
  * Implements ch_open().
  */
-    channel_T *
+    static channel_T *
 channel_open_func(typval_T *argvars)
 {
     char_u	*address;
@@ -1348,7 +1356,7 @@
 /*
  * Set the callback for "channel"/"part" for the response with "id".
  */
-    void
+    static void
 channel_set_req_callback(
 	channel_T   *channel,
 	ch_part_T   part,
@@ -2848,7 +2856,7 @@
 /*
  * Return TRUE if "channel" has JSON or other typeahead.
  */
-    int
+    static int
 channel_has_readahead(channel_T *channel, ch_part_T part)
 {
     ch_mode_T	ch_mode = channel->ch_part[part].ch_mode;
@@ -2959,7 +2967,7 @@
     dict_add_number(dict, namebuf, chanpart->ch_timeout);
 }
 
-    void
+    static void
 channel_info(channel_T *channel, dict_T *dict)
 {
     dict_add_number(dict, "id", channel->ch_id);
@@ -3067,7 +3075,7 @@
 /*
  * Close the "in" part channel "channel".
  */
-    void
+    static void
 channel_close_in(channel_T *channel)
 {
     ch_close_part(channel, PART_IN);
@@ -3676,7 +3684,7 @@
 /*
  * Common for ch_read() and ch_readraw().
  */
-    void
+    static void
 common_channel_read(typval_T *argvars, typval_T *rettv, int raw, int blob)
 {
     channel_T	*channel;
@@ -3762,7 +3770,7 @@
  * Lookup the channel from the socket.  Set "partp" to the fd index.
  * Returns NULL when the socket isn't found.
  */
-    channel_T *
+    static channel_T *
 channel_fd2channel(sock_T fd, ch_part_T *partp)
 {
     channel_T	*channel;
@@ -4092,7 +4100,7 @@
 /*
  * common for "ch_evalexpr()" and "ch_sendexpr()"
  */
-    void
+    static void
 ch_expr_common(typval_T *argvars, typval_T *rettv, int eval)
 {
     char_u	*text;
@@ -4154,7 +4162,7 @@
 /*
  * common for "ch_evalraw()" and "ch_sendraw()"
  */
-    void
+    static void
 ch_raw_common(typval_T *argvars, typval_T *rettv, int eval)
 {
     char_u	buf[NUMBUFLEN];
@@ -4540,7 +4548,7 @@
 /*
  * Return the "part" to write to for "channel".
  */
-    ch_part_T
+    static ch_part_T
 channel_part_send(channel_T *channel)
 {
     if (channel->CH_SOCK_FD == INVALID_FD)
@@ -4551,7 +4559,7 @@
 /*
  * Return the default "part" to read from for "channel".
  */
-    ch_part_T
+    static ch_part_T
 channel_part_read(channel_T *channel)
 {
     if (channel->CH_SOCK_FD == INVALID_FD)
@@ -4563,7 +4571,7 @@
  * Return the mode of "channel"/"part"
  * If "channel" is invalid returns MODE_JSON.
  */
-    ch_mode_T
+    static ch_mode_T
 channel_get_mode(channel_T *channel, ch_part_T part)
 {
     if (channel == NULL)
@@ -4574,7 +4582,7 @@
 /*
  * Return the timeout of "channel"/"part"
  */
-    int
+    static int
 channel_get_timeout(channel_T *channel, ch_part_T part)
 {
     return channel->ch_part[part].ch_timeout;
@@ -4638,7 +4646,7 @@
 /*
  * Free any members of a jobopt_T.
  */
-    void
+    static void
 free_job_options(jobopt_T *opt)
 {
     if (opt->jo_callback.cb_partial != NULL)
@@ -5309,7 +5317,7 @@
     }
 }
 
-job_T *jobs_to_free = NULL;
+static job_T *jobs_to_free = NULL;
 
 /*
  * Put "job" in a list to be freed later, when it's no longer referenced.