diff --git a/misc.c b/misc.c
index 25ed8636..4e8764fb 100644
--- a/misc.c
+++ b/misc.c
@@ -1258,7 +1258,6 @@ bool strendswith(const char *s, const char *t)
 char *buildinfo(const char *newline)
 {
     strbuf *buf = strbuf_new();
-    extern const char commitid[];      /* in commitid.c */
 
     strbuf_catf(buf, "Build platform: %d-bit %s",
                 (int)(CHAR_BIT * sizeof(void *)),
diff --git a/putty.h b/putty.h
index fdef2801..0f4ab6db 100644
--- a/putty.h
+++ b/putty.h
@@ -1709,6 +1709,7 @@ void ser_setup_config_box(struct controlbox *b, bool midsession,
  * Exports from version.c.
  */
 extern const char ver[];
+extern const char commitid[];
 
 /*
  * Exports from unicode.c.
@@ -1853,6 +1854,9 @@ void conf_filesel_handler(union control *ctrl, dlgparam *dlg,
 			  void *data, int event);
 void conf_fontsel_handler(union control *ctrl, dlgparam *dlg,
 			  void *data, int event);
+/* Much more special-purpose function needed by sercfg.c */
+void config_protocolbuttons_handler(union control *, dlgparam *, void *, int);
+
 void setup_config_box(struct controlbox *b, bool midsession,
 		      int protocol, int protcfginfo);
 
diff --git a/sercfg.c b/sercfg.c
index 2c1682f5..a5a3e3f4 100644
--- a/sercfg.c
+++ b/sercfg.c
@@ -132,8 +132,6 @@ void ser_setup_config_box(struct controlbox *b, bool midsession,
 
     if (!midsession) {
 	int i;
-        extern void config_protocolbuttons_handler(union control *, dlgparam *,
-						   void *, int);
 
 	/*
 	 * Add the serial back end to the protocols list at the
diff --git a/ssh.h b/ssh.h
index c657bca4..da98b7c8 100644
--- a/ssh.h
+++ b/ssh.h
@@ -185,6 +185,12 @@ void share_setup_x11_channel(ssh_sharing_connstate *cs, share_channel *chan,
                              int protomajor, int protominor,
                              const void *initial_data, int initial_len);
 
+/* Per-application overrides for what roles we can take in connection
+ * sharing, regardless of user configuration (e.g. pscp will never be
+ * an upstream) */
+extern const bool share_can_be_downstream;
+extern const bool share_can_be_upstream;
+
 struct X11Display;
 struct X11FakeAuth;
 
@@ -418,6 +424,8 @@ struct ec_point {
     bool infinity;
 };
 
+/* A couple of ECC functions exported for use outside sshecc.c */
+struct ec_point *ecp_mul(const struct ec_point *a, const Bignum b);
 void ec_point_free(struct ec_point *point);
 
 /* Weierstrass form curve */
diff --git a/ssh2connection.c b/ssh2connection.c
index 0be08aa6..f1135309 100644
--- a/ssh2connection.c
+++ b/ssh2connection.c
@@ -325,13 +325,6 @@ static bool ssh2_connection_filter_queue(struct ssh2_connection_state *s)
     ChanopenResult chanopen_result;
     PacketProtocolLayer *ppl = &s->ppl; /* for ppl_logevent */
 
-    /* Cross-reference to ssh2transport.c to handle the common packets
-     * between login and connection: DISCONNECT, DEBUG and IGNORE. If
-     * we have an instance of ssh2transport below us, then those
-     * messages won't come here anyway, but they could if we're
-     * running in bare ssh2-connection mode. */
-    extern bool ssh2_common_filter_queue(PacketProtocolLayer *ppl);
-
     while (1) {
         if (ssh2_common_filter_queue(&s->ppl))
             return true;
diff --git a/sshecdsag.c b/sshecdsag.c
index 7523fa7a..09d2eba3 100644
--- a/sshecdsag.c
+++ b/sshecdsag.c
@@ -4,9 +4,6 @@
 
 #include "ssh.h"
 
-/* Forward reference from sshecc.c */
-struct ec_point *ecp_mul(const struct ec_point *a, const Bignum b);
-
 int ec_generate(struct ec_key *key, int bits, progfn_t pfn,
                 void *pfnparam)
 {
diff --git a/sshppl.h b/sshppl.h
index 5069f871..80be9d14 100644
--- a/sshppl.h
+++ b/sshppl.h
@@ -134,6 +134,13 @@ void ssh_ppl_user_output_string_and_free(PacketProtocolLayer *ppl, char *text);
 ptrlen ssh2_transport_get_session_id(PacketProtocolLayer *ssh2_transport_ptr);
 void ssh2_transport_notify_auth_done(PacketProtocolLayer *ssh2_transport_ptr);
 
+/* Shared method between ssh2 layers (defined in ssh2transport.c) to
+ * handle the common packets between login and connection: DISCONNECT,
+ * DEBUG and IGNORE. Those messages are handled by the ssh2transport
+ * layer if we have one, but in bare ssh2-connection mode they have to
+ * be handled by ssh2connection. */
+bool ssh2_common_filter_queue(PacketProtocolLayer *ppl);
+
 /* Methods for ssh1login to pass protocol flags to ssh1connection */
 void ssh1_connection_set_protoflags(
     PacketProtocolLayer *ppl, int local, int remote);
diff --git a/sshrand.c b/sshrand.c
index 63211693..cde35eef 100644
--- a/sshrand.c
+++ b/sshrand.c
@@ -9,9 +9,6 @@
 /* Collect environmental noise every 5 minutes */
 #define NOISE_REGULAR_INTERVAL (5*60*TICKSPERSEC)
 
-void noise_get_heavy(void (*func) (void *, int));
-void noise_get_light(void (*func) (void *, int));
-
 /*
  * `pool' itself is a pool of random data which we actually use: we
  * return bytes from `pool', at position `poolpos', until `poolpos'
diff --git a/sshshare.c b/sshshare.c
index 48a0ca36..664a622e 100644
--- a/sshshare.c
+++ b/sshshare.c
@@ -1968,11 +1968,6 @@ static int share_listen_accepting(Plug *plug,
     return 0;
 }
 
-/* Per-application overrides for what roles we can take (e.g. pscp
- * will never be an upstream) */
-extern const bool share_can_be_downstream;
-extern const bool share_can_be_upstream;
-
 /*
  * Decide on the string used to identify the connection point between
  * upstream and downstream (be it a Windows named pipe or a
diff --git a/terminal.c b/terminal.c
index ae0f3917..013fcbc2 100644
--- a/terminal.c
+++ b/terminal.c
@@ -1051,7 +1051,6 @@ static void null_line_error(Terminal *term, int y, int lineno,
                             tree234 *whichtree, int treeindex,
                             const char *varname)
 {
-    extern const char commitid[]; /* in version.c */
     modalfatalbox("%s==NULL in terminal.c\n"
                   "lineno=%d y=%d w=%d h=%d\n"
                   "count(scrollback=%p)=%d\n"
diff --git a/unix/gtkapp.c b/unix/gtkapp.c
index 70dc7d3c..e7f49df5 100644
--- a/unix/gtkapp.c
+++ b/unix/gtkapp.c
@@ -107,8 +107,6 @@ void session_window_closed(void) {}
 void window_setup_error(const char *errmsg) {}
 #else /* GTK_CHECK_VERSION(3,0,0) */
 
-extern const bool use_event_log;
-
 static void startup(GApplication *app, gpointer user_data)
 {
     GMenu *menubar, *menu, *section;
@@ -216,7 +214,6 @@ GtkWidget *make_gtk_toplevel_window(GtkFrontend *frontend)
 
 void launch_duplicate_session(Conf *conf)
 {
-    extern const bool dup_check_launchable;
     assert(!dup_check_launchable || conf_launchable(conf));
     g_application_hold(G_APPLICATION(app));
     new_session_window(conf_copy(conf), NULL);
@@ -315,15 +312,11 @@ int main(int argc, char **argv)
 {
     int status;
 
-    {
-        /* Call the function in ux{putty,pterm}.c to do app-type
-         * specific setup */
-        extern void setup(bool);
-        setup(false);     /* false means we are not a one-session process */
-    }
+    /* Call the function in ux{putty,pterm}.c to do app-type
+     * specific setup */
+    setup(false);     /* false means we are not a one-session process */
 
     if (argc > 1) {
-        extern char *pty_osx_envrestore_prefix;
         pty_osx_envrestore_prefix = argv[--argc];
     }
 
diff --git a/unix/gtkdlg.c b/unix/gtkdlg.c
index 1d88d7fc..84f9774f 100644
--- a/unix/gtkdlg.c
+++ b/unix/gtkdlg.c
@@ -3189,15 +3189,7 @@ GtkWidget *create_config_box(const char *title, Conf *conf,
     dp->retval = -1;
     dp->window = window;
 
-    {
-	/* in gtkwin.c */
-	extern void set_window_icon(GtkWidget *window,
-				    const char *const *const *icon,
-				    int n_icon);
-	extern const char *const *const cfg_icon[];
-	extern const int n_cfg_icon;
-	set_window_icon(window, cfg_icon, n_cfg_icon);
-    }
+    set_window_icon(window, cfg_icon, n_cfg_icon);
 
 #if !GTK_CHECK_VERSION(2,0,0)
     gtk_scrolled_window_add_with_viewport(GTK_SCROLLED_WINDOW(treescroll),
@@ -3860,8 +3852,6 @@ static void eventlog_list_handler(union control *ctrl, dlgparam *dp,
 
         if (gtk_selection_owner_set(es->window, GDK_SELECTION_PRIMARY,
                                     GDK_CURRENT_TIME)) {
-            extern GdkAtom compound_text_atom;
-
             gtk_selection_add_target(es->window, GDK_SELECTION_PRIMARY,
                                      GDK_SELECTION_TYPE_STRING, 1);
             gtk_selection_add_target(es->window, GDK_SELECTION_PRIMARY,
diff --git a/unix/gtkmain.c b/unix/gtkmain.c
index e51b5c43..6a3d25ed 100644
--- a/unix/gtkmain.c
+++ b/unix/gtkmain.c
@@ -47,9 +47,6 @@
 static char *progname, **gtkargvstart;
 static int ngtkargs;
 
-extern char **pty_argv;	       /* declared in pty.c */
-extern bool use_pty_argv;
-
 static const char *app_name = "pterm";
 
 char *x_get_default(const char *key)
@@ -590,12 +587,9 @@ int main(int argc, char **argv)
 
     setlocale(LC_CTYPE, "");
 
-    {
-        /* Call the function in ux{putty,pterm}.c to do app-type
-         * specific setup */
-        extern void setup(bool);
-        setup(true);     /* true means we are a one-session process */
-    }
+    /* Call the function in ux{putty,pterm}.c to do app-type
+     * specific setup */
+    setup(true);         /* true means we are a one-session process */
 
     progname = argv[0];
 
@@ -626,8 +620,6 @@ int main(int argc, char **argv)
     block_signal(SIGPIPE, true);
 
     if (argc > 1 && !strncmp(argv[1], "---", 3)) {
-        extern const bool dup_check_launchable;
-
 	read_dupsession_data(conf, argv[1]);
 	/* Splatter this argument so it doesn't clutter a ps listing */
 	smemclr(argv[1], strlen(argv[1]));
diff --git a/unix/gtkwin.c b/unix/gtkwin.c
index c4269dd5..369e9942 100644
--- a/unix/gtkwin.c
+++ b/unix/gtkwin.c
@@ -5468,11 +5468,7 @@ void new_session_window(Conf *conf, const char *geometry_string)
 #endif
         );
 
-    {
-	extern const char *const *const main_icon[];
-	extern const int n_main_icon;
-	set_window_icon(inst->window, main_icon, n_main_icon);
-    }
+    set_window_icon(inst->window, main_icon, n_main_icon);
 
     gtk_widget_show(inst->window);
 
@@ -5484,7 +5480,6 @@ void new_session_window(Conf *conf, const char *geometry_string)
     {
 	GtkWidget *menuitem;
 	char *s;
-	extern const bool use_event_log, new_session, saved_sessions;
 
 	inst->menu = gtk_menu_new();
 
diff --git a/unix/unix.h b/unix/unix.h
index 1ce587bd..1a74492a 100644
--- a/unix/unix.h
+++ b/unix/unix.h
@@ -189,7 +189,14 @@ enum MenuAction {
 };
 void app_menu_action(GtkFrontend *frontend, enum MenuAction);
 
-/* Things gtkdlg.c needs from pterm.c */
+/* Arrays of pixmap data used for GTK window icons. (main_icon is for
+ * the process's main window; cfg_icon is the modified icon used for
+ * its config box.) */
+extern const char *const *const main_icon[];
+extern const char *const *const cfg_icon[];
+extern const int n_main_icon, n_cfg_icon;
+
+/* Things gtkdlg.c needs from gtkwin.c */
 #ifdef MAY_REFER_TO_GTK_IN_HEADERS
 enum DialogSlot {
     DIALOG_SLOT_RECONFIGURE,
@@ -202,9 +209,12 @@ enum DialogSlot {
 GtkWidget *gtk_seat_get_window(Seat *seat);
 void register_dialog(Seat *seat, enum DialogSlot slot, GtkWidget *dialog);
 void unregister_dialog(Seat *seat, enum DialogSlot slot);
+void set_window_icon(GtkWidget *window, const char *const *const *icon,
+                     int n_icon);
+extern GdkAtom compound_text_atom;
 #endif
 
-/* Things pterm.c needs from gtkdlg.c */
+/* Things gtkwin.c needs from gtkdlg.c */
 #ifdef MAY_REFER_TO_GTK_IN_HEADERS
 GtkWidget *create_config_box(const char *title, Conf *conf,
                              bool midsession, int protcfginfo,
@@ -247,18 +257,52 @@ GtkWidget *create_message_box(
     post_dialog_fn_t after, void *afterctx);
 #endif
 
-/* Things pterm.c needs from {ptermm,uxputty}.c */
+/* Things gtkwin.c needs from {ptermm,uxputty}.c */
 char *make_default_wintitle(char *hostname);
 
-/* pterm.c needs this special function in xkeysym.c */
+/* gtkwin.c needs this special function in xkeysym.c */
 int keysym_to_unicode(int keysym);
 
-/* Things uxstore.c needs from pterm.c */
+/* Things uxstore.c needs from gtkwin.c */
 char *x_get_default(const char *key);
 
-/* Things uxstore.c provides to pterm.c */
+/* Things uxstore.c provides to gtkwin.c */
 void provide_xrm_string(char *string);
 
+/* Function that {gtkapp,gtkmain}.c needs from ux{pterm,putty}.c. Does
+ * early process setup that varies between applications (e.g.
+ * pty_pre_init or sk_init), and is passed a boolean by the caller
+ * indicating whether this is an OS X style multi-session monolithic
+ * process or an ordinary Unix one-shot. */
+void setup(bool single_session_in_this_process);
+
+/*
+ * Per-application constants that affect behaviour of shared modules.
+ */
+/* Do we need an Event Log menu item? (yes for PuTTY, no for pterm) */
+extern const bool use_event_log;
+/* Do we need a New Session menu item? (yes for PuTTY, no for pterm) */
+extern const bool new_session;
+/* Do we need a Saved Sessions menu item? (yes for PuTTY, no for pterm) */
+extern const bool saved_sessions;
+/* When we Duplicate Session, do we need to double-check that the Conf
+ * is in a launchable state? (no for pterm, because conf_launchable
+ * returns an irrelevant answer, since we'll force use of the pty
+ * backend which ignores all the relevant settings) */
+extern const bool dup_check_launchable;
+/* In the Duplicate Session serialised data, do we send/receive an
+ * argv array after the main Conf? (yes for pterm, no for PuTTY) */
+extern const bool use_pty_argv;
+
+/*
+ * OS X environment munging: this is the prefix we expect to find on
+ * environment variable names that were changed by osxlaunch.
+ * Extracted from the command line of the OS X pterm main binary, and
+ * used in uxpty.c to restore the original environment before
+ * launching its subprocess.
+ */
+extern char *pty_osx_envrestore_prefix;
+
 /* Things provided by uxcons.c */
 struct termios;
 void stderr_tty_init(void);
@@ -360,4 +404,25 @@ Socket *make_fd_socket(int infd, int outfd, int inerrfd, Plug *plug);
 #define DEFAULT_GTK_FONT "server:fixed"
 #endif
 
-#endif
+/*
+ * uxpty.c.
+ */
+void pty_pre_init(void);    /* pty+utmp setup before dropping privilege */
+/* Pass in the argv[] for an instance of the pty backend created by
+ * the standard vtable constructor. Only called from (non-OSX) pterm,
+ * which will construct exactly one such instance, and initialises
+ * this from the command line. */
+extern char **pty_argv;
+
+/*
+ * gtkask.c.
+ */
+char *gtk_askpass_main(const char *display, const char *wintitle,
+                       const char *prompt, bool *success);
+
+/*
+ * uxsftpserver.c.
+ */
+extern const SftpServerVtable unix_live_sftpserver_vt;
+
+#endif /* PUTTY_UNIX_H */
diff --git a/unix/uxpgnt.c b/unix/uxpgnt.c
index 42ce7ba5..907e69a4 100644
--- a/unix/uxpgnt.c
+++ b/unix/uxpgnt.c
@@ -349,10 +349,6 @@ static char *askpass_gui(const char *prompt)
     char *passphrase;
     bool success;
 
-    /* in gtkask.c */
-    char *gtk_askpass_main(const char *display, const char *wintitle,
-                           const char *prompt, bool *success);
-
     passphrase = gtk_askpass_main(
         display, "Pageant passphrase prompt", prompt, &success);
     if (!success) {
diff --git a/unix/uxpterm.c b/unix/uxpterm.c
index 1be68f50..27738a3d 100644
--- a/unix/uxpterm.c
+++ b/unix/uxpterm.c
@@ -43,8 +43,6 @@ char *make_default_wintitle(char *hostname)
 
 void setup(bool single)
 {
-    extern void pty_pre_init(void);    /* declared in pty.c */
-
     cmdline_tooltype = TOOLTYPE_NONNETWORK;
     default_protocol = -1;
 
diff --git a/unix/uxserver.c b/unix/uxserver.c
index 7b9ab0f0..470e34d6 100644
--- a/unix/uxserver.c
+++ b/unix/uxserver.c
@@ -355,8 +355,6 @@ static bool longoptarg(const char *arg, const char *expected,
     return false;
 }
 
-extern const SftpServerVtable unix_live_sftpserver_vt;
-
 int main(int argc, char **argv)
 {
     int *fdlist;
diff --git a/unix/uxshare.c b/unix/uxshare.c
index a7d7fc12..d11d6bb8 100644
--- a/unix/uxshare.c
+++ b/unix/uxshare.c
@@ -23,12 +23,6 @@
 #define SALT_FILENAME "salt"
 #define SALT_SIZE 64
 
-/*
- * Functions provided by uxnet.c to help connection sharing.
- */
-SockAddr *unix_sock_addr(const char *path);
-Socket *new_unix_listener(SockAddr *listenaddr, Plug *plug);
-
 static char *make_parentdir_name(void)
 {
     char *username, *parent;
diff --git a/windows/windlg.c b/windows/windlg.c
index 4019b9a3..16abe3ff 100644
--- a/windows/windlg.c
+++ b/windows/windlg.c
@@ -49,8 +49,6 @@ static char *events_initial[LOGEVENT_INITIAL_MAX];
 static char *events_circular[LOGEVENT_CIRCULAR_MAX];
 static int ninitial = 0, ncircular = 0, circular_first = 0;
 
-extern Conf *conf;		       /* defined in window.c */
-
 #define PRINTER_DISABLED_STRING "None (printing disabled)"
 
 void force_normal(HWND hwnd)
@@ -799,7 +797,6 @@ static void win_gui_eventlog(LogPolicy *lp, const char *string)
 
 static void win_gui_logging_error(LogPolicy *lp, const char *event)
 {
-    extern Seat win_seat[1];
     /* Send 'can't open log file' errors to the terminal window.
      * (Marked as stderr, although terminal.c won't care.) */
     seat_stderr(win_seat, event, strlen(event));
diff --git a/windows/window.c b/windows/window.c
index 31b1cbe5..913e453d 100644
--- a/windows/window.c
+++ b/windows/window.c
@@ -152,8 +152,6 @@ struct wm_netevent_params {
     LPARAM lParam;
 };
 
-Conf *conf;			       /* exported to windlg.c */
-
 static void conf_cache_data(void);
 int cursor_type;
 int vtmode;
@@ -349,7 +347,8 @@ static const SeatVtable win_seat_vt = {
     nullseat_get_windowid,
     win_seat_get_window_pixel_size,
 };
-Seat win_seat[1] = {{ &win_seat_vt }};
+static Seat win_seat_impl = { &win_seat_vt };
+Seat *const win_seat = &win_seat_impl;
 
 static void start_backend(void)
 {
diff --git a/windows/winnet.c b/windows/winnet.c
index 459d584a..bf91634f 100644
--- a/windows/winnet.c
+++ b/windows/winnet.c
@@ -839,8 +839,6 @@ static void sk_net_set_frozen(Socket *s, bool is_frozen);
 static const char *sk_net_socket_error(Socket *s);
 static SocketPeerInfo *sk_net_peer_info(Socket *s);
 
-extern char *do_select(SOCKET skt, bool startup);
-
 static const SocketVtable NetSocket_sockvt = {
     sk_net_plug,
     sk_net_close,
@@ -1790,7 +1788,7 @@ SOCKET next_socket(int *state)
     return s ? s->s : INVALID_SOCKET;
 }
 
-extern bool socket_writable(SOCKET skt)
+bool socket_writable(SOCKET skt)
 {
     NetSocket *s = find234(sktree, (void *)skt, cmpforsearch);
 
diff --git a/windows/winnpc.c b/windows/winnpc.c
index 31906e0d..4fcb9e26 100644
--- a/windows/winnpc.c
+++ b/windows/winnpc.c
@@ -15,9 +15,6 @@
 
 #include "winsecur.h"
 
-Socket *make_handle_socket(HANDLE send_H, HANDLE recv_H, HANDLE stderr_H,
-                           Plug *plug, bool overlapped);
-
 Socket *new_named_pipe_client(const char *pipename, Plug *plug)
 {
     HANDLE pipehandle;
diff --git a/windows/winnps.c b/windows/winnps.c
index d355a90a..fa1d804b 100644
--- a/windows/winnps.c
+++ b/windows/winnps.c
@@ -15,9 +15,6 @@
 
 #include "winsecur.h"
 
-Socket *make_handle_socket(HANDLE send_H, HANDLE recv_H, HANDLE stderr_H,
-                           Plug *plug, bool overlapped);
-
 typedef struct NamedPipeServerSocket {
     /* Parameters for (repeated) creation of named pipe objects */
     PSECURITY_DESCRIPTOR psd;
@@ -120,12 +117,6 @@ static Socket *named_pipe_accept(accept_ctx_t ctx, Plug *plug)
     return make_handle_socket(conn, conn, NULL, plug, true);
 }
 
-/*
- * Dummy SockAddr *type which just holds a named pipe address. Only
- * used for calling plug_log from named_pipe_accept_loop() here.
- */
-SockAddr *sk_namedpipe_addr(const char *pipename);
-
 static void named_pipe_accept_loop(NamedPipeServerSocket *ps,
                                    bool got_one_already)
 {
diff --git a/windows/winpgen.c b/windows/winpgen.c
index 6d5c244b..833ef393 100644
--- a/windows/winpgen.c
+++ b/windows/winpgen.c
@@ -137,8 +137,6 @@ static void progress_update(void *param, int action, int phase, int iprogress)
     }
 }
 
-extern const char ver[];
-
 struct PassphraseProcStruct {
     char **passphrase;
     char *comment;
diff --git a/windows/winpgnt.c b/windows/winpgnt.c
index f8320f4a..bf84e863 100644
--- a/windows/winpgnt.c
+++ b/windows/winpgnt.c
@@ -50,8 +50,6 @@
 
 #define APPNAME "Pageant"
 
-extern const char ver[];
-
 static HWND keylist;
 static HWND aboutbox;
 static HMENU systray_menu, session_menu;
diff --git a/windows/winplink.c b/windows/winplink.c
index 493db000..1f47dd9b 100644
--- a/windows/winplink.c
+++ b/windows/winplink.c
@@ -530,7 +530,6 @@ int main(int argc, char **argv)
 	} else if (n == WAIT_OBJECT_0 + nhandles) {
 	    WSANETWORKEVENTS things;
 	    SOCKET socket;
-	    extern SOCKET first_socket(int *), next_socket(int *);
 	    int i, socketstate;
 
 	    /*
diff --git a/windows/winproxy.c b/windows/winproxy.c
index 73b77d42..909af2f1 100644
--- a/windows/winproxy.c
+++ b/windows/winproxy.c
@@ -12,9 +12,6 @@
 #include "network.h"
 #include "proxy.h"
 
-Socket *make_handle_socket(HANDLE send_H, HANDLE recv_H, HANDLE stderr_H,
-                           Plug *plug, bool overlapped);
-
 Socket *platform_new_connection(SockAddr *addr, const char *hostname,
                                 int port, bool privport,
                                 bool oobinline, bool nodelay, bool keepalive,
diff --git a/windows/winsftp.c b/windows/winsftp.c
index 7d0adde5..f9f6222c 100644
--- a/windows/winsftp.c
+++ b/windows/winsftp.c
@@ -535,7 +535,6 @@ int do_eventsel_loop(HANDLE other_event)
     } else if (netindex >= 0 && n == WAIT_OBJECT_0 + netindex) {
 	WSANETWORKEVENTS things;
 	SOCKET socket;
-	extern SOCKET first_socket(int *), next_socket(int *);
 	int i, socketstate;
 
 	/*
diff --git a/windows/winshare.c b/windows/winshare.c
index 5d98cc17..6498cc4e 100644
--- a/windows/winshare.c
+++ b/windows/winshare.c
@@ -115,9 +115,6 @@ static char *make_name(const char *prefix, const char *name)
     return retname;
 }
 
-Socket *new_named_pipe_client(const char *pipename, Plug *plug);
-Socket *new_named_pipe_listener(const char *pipename, Plug *plug);
-
 int platform_ssh_share(const char *pi_name, Conf *conf,
                        Plug *downplug, Plug *upplug, Socket **sock,
                        char **logtext, char **ds_err, char **us_err,
diff --git a/windows/winstuff.h b/windows/winstuff.h
index 4d735af1..cd128156 100644
--- a/windows/winstuff.h
+++ b/windows/winstuff.h
@@ -235,13 +235,16 @@ void quit_help(HWND hwnd);
 /*
  * The terminal and logging context are notionally local to the
  * Windows front end, but they must be shared between window.c and
- * windlg.c. Likewise the Seat structure for the Windows GUI.
+ * windlg.c. Likewise the Seat structure for the Windows GUI, and the
+ * Conf for the main session..
  */
 GLOBAL Terminal *term;
 GLOBAL LogContext *logctx;
+GLOBAL Conf *conf;
 
 /*
- * GUI seat methods in windlg.c.
+ * GUI seat methods in windlg.c, so that the vtable definition in
+ * window.c can refer to them.
  */
 int win_seat_verify_ssh_host_key(
     Seat *seat, const char *host, int port,
@@ -254,6 +257,12 @@ int win_seat_confirm_weak_cached_hostkey(
     Seat *seat, const char *algname, const char *betteralgs,
     void (*callback)(void *ctx, int result), void *ctx);
 
+/*
+ * The Windows GUI seat object itself, so that its methods can be
+ * called outside window.c.
+ */
+extern Seat *const win_seat;
+
 /*
  * Windows-specific clipboard helper function shared with windlg.c,
  * which takes the data string in the system code page instead of
@@ -303,7 +312,17 @@ void write_aclip(int clipboard, char *, int, bool);
 /*
  * Exports from winnet.c.
  */
-extern void select_result(WPARAM, LPARAM);
+/* Report an event notification from WSA*Select */
+void select_result(WPARAM, LPARAM);
+/* Enumerate all currently live OS-level SOCKETs */
+SOCKET first_socket(int *);
+SOCKET next_socket(int *);
+/* Ask winnet.c whether we currently want to try to write to a SOCKET */
+bool socket_writable(SOCKET skt);
+/* Force a refresh of the SOCKET list by re-calling do_select for each one */
+void socket_reselect_all(void);
+/* Make a SockAddr which just holds a named pipe address. */
+SockAddr *sk_namedpipe_addr(const char *pipename);
 
 /*
  * winnet.c dynamically loads WinSock 2 or WinSock 1 depending on
@@ -331,9 +350,19 @@ DECL_WINDOWS_FUNCTION(GLOBAL, int, select,
 		       fd_set FAR *, const struct timeval FAR *));
 #endif
 
-extern bool socket_writable(SOCKET skt);
+/*
+ * Provided by each client of winnet.c, and called by winnet.c to turn
+ * on or off WSA*Select for a given socket.
+ */
+char *do_select(SOCKET skt, bool startup);
 
-extern void socket_reselect_all(void);
+/*
+ * Network-subsystem-related functions provided in other Windows modules.
+ */
+Socket *make_handle_socket(HANDLE send_H, HANDLE recv_H, HANDLE stderr_H,
+                           Plug *plug, bool overlapped); /* winhsock */
+Socket *new_named_pipe_client(const char *pipename, Plug *plug); /* winnpc */
+Socket *new_named_pipe_listener(const char *pipename, Plug *plug); /* winnps */
 
 /*
  * Exports from winctrls.c.