diff --git a/Recipe b/Recipe
index f02f1680..e1e7f93e 100644
--- a/Recipe
+++ b/Recipe
@@ -244,10 +244,10 @@ TERMINAL = terminal stripctrl wcwidth logging tree234 minibidi
 
 # GUI front end and terminal emulator (putty, puttytel).
 GUITERM  = TERMINAL window windlg winctrls sizetip winprint winutils
-	 + wincfg sercfg winhelp winjump sessprep winselgui
+	 + wincfg winhelp winjump sessprep winselgui
 
 # Same thing on Unix.
-UXTERM   = TERMINAL uxcfg sercfg uxucs uxprint timing callback miscucs
+UXTERM   = TERMINAL uxcfg uxucs uxprint timing callback miscucs
 GTKTERM  = UXTERM gtkwin gtkcfg gtkdlg gtkfont gtkcols gtkmisc xkeysym
 	 + x11misc gtkcomm sessprep
 GTKMAIN  = gtkmain cmdline
diff --git a/config.c b/config.c
index 71a903bf..6388144e 100644
--- a/config.c
+++ b/config.c
@@ -1469,6 +1469,114 @@ static void clipboard_control(struct controlset *s, const char *label,
 #endif
 }
 
+static void serial_parity_handler(union control *ctrl, dlgparam *dlg,
+                                  void *data, int event)
+{
+    static const struct {
+        const char *name;
+        int val;
+    } parities[] = {
+        {"None", SER_PAR_NONE},
+        {"Odd", SER_PAR_ODD},
+        {"Even", SER_PAR_EVEN},
+        {"Mark", SER_PAR_MARK},
+        {"Space", SER_PAR_SPACE},
+    };
+    int mask = ctrl->listbox.context.i;
+    int i, j;
+    Conf *conf = (Conf *)data;
+
+    if (event == EVENT_REFRESH) {
+        /* Fetching this once at the start of the function ensures we
+         * remember what the right value is supposed to be when
+         * operations below cause reentrant calls to this function. */
+        int oldparity = conf_get_int(conf, CONF_serparity);
+
+        dlg_update_start(ctrl, dlg);
+        dlg_listbox_clear(ctrl, dlg);
+        for (i = 0; i < lenof(parities); i++)  {
+            if (mask & (1 << parities[i].val))
+                dlg_listbox_addwithid(ctrl, dlg, parities[i].name,
+                                      parities[i].val);
+        }
+        for (i = j = 0; i < lenof(parities); i++) {
+            if (mask & (1 << parities[i].val)) {
+                if (oldparity == parities[i].val) {
+                    dlg_listbox_select(ctrl, dlg, j);
+                    break;
+                }
+                j++;
+            }
+        }
+        if (i == lenof(parities)) {    /* an unsupported setting was chosen */
+            dlg_listbox_select(ctrl, dlg, 0);
+            oldparity = SER_PAR_NONE;
+        }
+        dlg_update_done(ctrl, dlg);
+        conf_set_int(conf, CONF_serparity, oldparity);    /* restore */
+    } else if (event == EVENT_SELCHANGE) {
+        int i = dlg_listbox_index(ctrl, dlg);
+        if (i < 0)
+            i = SER_PAR_NONE;
+        else
+            i = dlg_listbox_getid(ctrl, dlg, i);
+        conf_set_int(conf, CONF_serparity, i);
+    }
+}
+
+static void serial_flow_handler(union control *ctrl, dlgparam *dlg,
+                                void *data, int event)
+{
+    static const struct {
+        const char *name;
+        int val;
+    } flows[] = {
+        {"None", SER_FLOW_NONE},
+        {"XON/XOFF", SER_FLOW_XONXOFF},
+        {"RTS/CTS", SER_FLOW_RTSCTS},
+        {"DSR/DTR", SER_FLOW_DSRDTR},
+    };
+    int mask = ctrl->listbox.context.i;
+    int i, j;
+    Conf *conf = (Conf *)data;
+
+    if (event == EVENT_REFRESH) {
+        /* Fetching this once at the start of the function ensures we
+         * remember what the right value is supposed to be when
+         * operations below cause reentrant calls to this function. */
+        int oldflow = conf_get_int(conf, CONF_serflow);
+
+        dlg_update_start(ctrl, dlg);
+        dlg_listbox_clear(ctrl, dlg);
+        for (i = 0; i < lenof(flows); i++)  {
+            if (mask & (1 << flows[i].val))
+                dlg_listbox_addwithid(ctrl, dlg, flows[i].name, flows[i].val);
+        }
+        for (i = j = 0; i < lenof(flows); i++) {
+            if (mask & (1 << flows[i].val)) {
+                if (oldflow == flows[i].val) {
+                    dlg_listbox_select(ctrl, dlg, j);
+                    break;
+                }
+                j++;
+            }
+        }
+        if (i == lenof(flows)) {       /* an unsupported setting was chosen */
+            dlg_listbox_select(ctrl, dlg, 0);
+            oldflow = SER_FLOW_NONE;
+        }
+        dlg_update_done(ctrl, dlg);
+        conf_set_int(conf, CONF_serflow, oldflow);/* restore */
+    } else if (event == EVENT_SELCHANGE) {
+        int i = dlg_listbox_index(ctrl, dlg);
+        if (i < 0)
+            i = SER_FLOW_NONE;
+        else
+            i = dlg_listbox_getid(ctrl, dlg, i);
+        conf_set_int(conf, CONF_serflow, i);
+    }
+}
+
 void setup_config_box(struct controlbox *b, bool midsession,
                       int protocol, int protcfginfo)
 {
@@ -2316,13 +2424,22 @@ void setup_config_box(struct controlbox *b, bool midsession,
     }
 
     /*
-     * All the SSH stuff is omitted in PuTTYtel, or in a reconfig
-     * when we're not doing SSH.
+     * Each per-protocol configuration GUI panel is conditionally
+     * displayed. We don't display it if this binary doesn't contain a
+     * backend for its protocol at all; we don't display it if we're
+     * already in mid-session with a different protocol selected; and
+     * even if we _do_ have this protocol selected, we don't display
+     * the panel if the protocol doesn't permit any mid-session
+     * reconfiguration anyway.
      */
 
-    if (backend_vt_from_proto(PROT_SSH) &&
-        (!midsession || protocol == PROT_SSH)) {
+#define DISPLAY_RECONFIGURABLE_PROTOCOL(which_proto) \
+    (backend_vt_from_proto(which_proto) && \
+     (!midsession || protocol == (which_proto)))
+#define DISPLAY_NON_RECONFIGURABLE_PROTOCOL(which_proto) \
+    (backend_vt_from_proto(which_proto) && !midsession)
 
+    if (DISPLAY_RECONFIGURABLE_PROTOCOL(PROT_SSH)) {
         /*
          * The Connection/SSH panel.
          */
@@ -2828,11 +2945,50 @@ void setup_config_box(struct controlbox *b, bool midsession,
         }
     }
 
-    /*
-     * The Telnet panel exists in the base config box, and in a
-     * mid-session reconfig box _if_ we're using Telnet.
-     */
-    if (!midsession || protocol == PROT_TELNET) {
+    if (DISPLAY_RECONFIGURABLE_PROTOCOL(PROT_SERIAL)) {
+        const BackendVtable *ser_vt = backend_vt_from_proto(PROT_SERIAL);
+
+        /*
+         * The Connection/Serial panel.
+         */
+        ctrl_settitle(b, "Connection/Serial",
+                      "Options controlling local serial lines");
+
+        if (!midsession) {
+            /*
+             * We don't permit switching to a different serial port in
+             * midflight, although we do allow all other
+             * reconfiguration.
+             */
+            s = ctrl_getset(b, "Connection/Serial", "serline",
+                            "Select a serial line");
+            ctrl_editbox(s, "Serial line to connect to", 'l', 40,
+                         HELPCTX(serial_line),
+                         conf_editbox_handler, I(CONF_serline), I(1));
+        }
+
+        s = ctrl_getset(b, "Connection/Serial", "sercfg", "Configure the serial line");
+        ctrl_editbox(s, "Speed (baud)", 's', 40,
+                     HELPCTX(serial_speed),
+                     conf_editbox_handler, I(CONF_serspeed), I(-1));
+        ctrl_editbox(s, "Data bits", 'b', 40,
+                     HELPCTX(serial_databits),
+                     conf_editbox_handler, I(CONF_serdatabits), I(-1));
+        /*
+         * Stop bits come in units of one half.
+         */
+        ctrl_editbox(s, "Stop bits", 't', 40,
+                     HELPCTX(serial_stopbits),
+                     conf_editbox_handler, I(CONF_serstopbits), I(-2));
+        ctrl_droplist(s, "Parity", 'p', 40,
+                      HELPCTX(serial_parity), serial_parity_handler,
+                      I(ser_vt->serial_parity_mask));
+        ctrl_droplist(s, "Flow control", 'f', 40,
+                      HELPCTX(serial_flow), serial_flow_handler,
+                      I(ser_vt->serial_flow_mask));
+    }
+
+    if (DISPLAY_RECONFIGURABLE_PROTOCOL(PROT_TELNET)) {
         /*
          * The Connection/Telnet panel.
          */
@@ -2866,8 +3022,7 @@ void setup_config_box(struct controlbox *b, bool midsession,
                       I(CONF_telnet_newline));
     }
 
-    if (!midsession) {
-
+    if (DISPLAY_NON_RECONFIGURABLE_PROTOCOL(PROT_RLOGIN)) {
         /*
          * The Connection/Rlogin panel.
          */
@@ -2880,8 +3035,11 @@ void setup_config_box(struct controlbox *b, bool midsession,
                      HELPCTX(rlogin_localuser),
                      conf_editbox_handler, I(CONF_localusername), I(1));
 
+    }
+
+    if (DISPLAY_NON_RECONFIGURABLE_PROTOCOL(PROT_SUPDUP)) {
         /*
-         * The Protocol/SUPDUP panel.
+         * The Connection/SUPDUP panel.
          */
         ctrl_settitle(b, "Connection/SUPDUP",
                       "Enabling and disabling SUPDUP user options");
diff --git a/putty.h b/putty.h
index 0a7390a9..662e6db1 100644
--- a/putty.h
+++ b/putty.h
@@ -534,6 +534,10 @@ struct BackendVtable {
     int protocol;
     int default_port;
     unsigned flags;
+
+    /* Only relevant for the serial protocol: bit masks of which
+     * parity and flow control settings are supported. */
+    unsigned serial_parity_mask, serial_flow_mask;
 };
 
 static inline const char *backend_init(
diff --git a/sercfg.c b/sercfg.c
deleted file mode 100644
index b54499a0..00000000
--- a/sercfg.c
+++ /dev/null
@@ -1,171 +0,0 @@
-/*
- * sercfg.c - the serial-port specific parts of the PuTTY
- * configuration box. Centralised as cross-platform code because
- * more than one platform will want to use it, but not part of the
- * main configuration. The expectation is that each platform's
- * local config function will call out to ser_setup_config_box() if
- * it needs to set up the standard serial stuff. (Of course, it can
- * then apply local tweaks after ser_setup_config_box() returns, if
- * it needs to.)
- */
-
-#include <assert.h>
-#include <stdlib.h>
-
-#include "putty.h"
-#include "dialog.h"
-#include "storage.h"
-
-static void serial_parity_handler(union control *ctrl, dlgparam *dlg,
-                                  void *data, int event)
-{
-    static const struct {
-        const char *name;
-        int val;
-    } parities[] = {
-        {"None", SER_PAR_NONE},
-        {"Odd", SER_PAR_ODD},
-        {"Even", SER_PAR_EVEN},
-        {"Mark", SER_PAR_MARK},
-        {"Space", SER_PAR_SPACE},
-    };
-    int mask = ctrl->listbox.context.i;
-    int i, j;
-    Conf *conf = (Conf *)data;
-
-    if (event == EVENT_REFRESH) {
-        /* Fetching this once at the start of the function ensures we
-         * remember what the right value is supposed to be when
-         * operations below cause reentrant calls to this function. */
-        int oldparity = conf_get_int(conf, CONF_serparity);
-
-        dlg_update_start(ctrl, dlg);
-        dlg_listbox_clear(ctrl, dlg);
-        for (i = 0; i < lenof(parities); i++)  {
-            if (mask & (1 << i))
-                dlg_listbox_addwithid(ctrl, dlg, parities[i].name,
-                                      parities[i].val);
-        }
-        for (i = j = 0; i < lenof(parities); i++) {
-            if (mask & (1 << i)) {
-                if (oldparity == parities[i].val) {
-                    dlg_listbox_select(ctrl, dlg, j);
-                    break;
-                }
-                j++;
-            }
-        }
-        if (i == lenof(parities)) {    /* an unsupported setting was chosen */
-            dlg_listbox_select(ctrl, dlg, 0);
-            oldparity = SER_PAR_NONE;
-        }
-        dlg_update_done(ctrl, dlg);
-        conf_set_int(conf, CONF_serparity, oldparity);    /* restore */
-    } else if (event == EVENT_SELCHANGE) {
-        int i = dlg_listbox_index(ctrl, dlg);
-        if (i < 0)
-            i = SER_PAR_NONE;
-        else
-            i = dlg_listbox_getid(ctrl, dlg, i);
-        conf_set_int(conf, CONF_serparity, i);
-    }
-}
-
-static void serial_flow_handler(union control *ctrl, dlgparam *dlg,
-                                void *data, int event)
-{
-    static const struct {
-        const char *name;
-        int val;
-    } flows[] = {
-        {"None", SER_FLOW_NONE},
-        {"XON/XOFF", SER_FLOW_XONXOFF},
-        {"RTS/CTS", SER_FLOW_RTSCTS},
-        {"DSR/DTR", SER_FLOW_DSRDTR},
-    };
-    int mask = ctrl->listbox.context.i;
-    int i, j;
-    Conf *conf = (Conf *)data;
-
-    if (event == EVENT_REFRESH) {
-        /* Fetching this once at the start of the function ensures we
-         * remember what the right value is supposed to be when
-         * operations below cause reentrant calls to this function. */
-        int oldflow = conf_get_int(conf, CONF_serflow);
-
-        dlg_update_start(ctrl, dlg);
-        dlg_listbox_clear(ctrl, dlg);
-        for (i = 0; i < lenof(flows); i++)  {
-            if (mask & (1 << i))
-                dlg_listbox_addwithid(ctrl, dlg, flows[i].name, flows[i].val);
-        }
-        for (i = j = 0; i < lenof(flows); i++) {
-            if (mask & (1 << i)) {
-                if (oldflow == flows[i].val) {
-                    dlg_listbox_select(ctrl, dlg, j);
-                    break;
-                }
-                j++;
-            }
-        }
-        if (i == lenof(flows)) {       /* an unsupported setting was chosen */
-            dlg_listbox_select(ctrl, dlg, 0);
-            oldflow = SER_FLOW_NONE;
-        }
-        dlg_update_done(ctrl, dlg);
-        conf_set_int(conf, CONF_serflow, oldflow);/* restore */
-    } else if (event == EVENT_SELCHANGE) {
-        int i = dlg_listbox_index(ctrl, dlg);
-        if (i < 0)
-            i = SER_FLOW_NONE;
-        else
-            i = dlg_listbox_getid(ctrl, dlg, i);
-        conf_set_int(conf, CONF_serflow, i);
-    }
-}
-
-void ser_setup_config_box(struct controlbox *b, bool midsession,
-                          int parity_mask, int flow_mask)
-{
-    struct controlset *s;
-
-    /*
-     * Entirely new Connection/Serial panel for serial port
-     * configuration.
-     */
-    ctrl_settitle(b, "Connection/Serial",
-                  "Options controlling local serial lines");
-
-    if (!midsession) {
-        /*
-         * We don't permit switching to a different serial port in
-         * midflight, although we do allow all other
-         * reconfiguration.
-         */
-        s = ctrl_getset(b, "Connection/Serial", "serline",
-                        "Select a serial line");
-        ctrl_editbox(s, "Serial line to connect to", 'l', 40,
-                     HELPCTX(serial_line),
-                     conf_editbox_handler, I(CONF_serline), I(1));
-    }
-
-    s = ctrl_getset(b, "Connection/Serial", "sercfg", "Configure the serial line");
-    ctrl_editbox(s, "Speed (baud)", 's', 40,
-                 HELPCTX(serial_speed),
-                 conf_editbox_handler, I(CONF_serspeed), I(-1));
-    ctrl_editbox(s, "Data bits", 'b', 40,
-                 HELPCTX(serial_databits),
-                 conf_editbox_handler, I(CONF_serdatabits), I(-1));
-    /*
-     * Stop bits come in units of one half.
-     */
-    ctrl_editbox(s, "Stop bits", 't', 40,
-                 HELPCTX(serial_stopbits),
-                 conf_editbox_handler, I(CONF_serstopbits), I(-2));
-    ctrl_droplist(s, "Parity", 'p', 40,
-                  HELPCTX(serial_parity),
-                  serial_parity_handler, I(parity_mask));
-    ctrl_droplist(s, "Flow control", 'f', 40,
-                  HELPCTX(serial_flow),
-                  serial_flow_handler, I(flow_mask));
-}
diff --git a/unix/uxcfg.c b/unix/uxcfg.c
index 6856bbfe..8397a0ac 100644
--- a/unix/uxcfg.c
+++ b/unix/uxcfg.c
@@ -67,13 +67,4 @@ void unix_setup_config_box(struct controlbox *b, bool midsession, int protocol)
             }
         }
     }
-
-    /*
-     * Serial back end is available on Unix. However, we have to
-     * mask out a couple of the configuration options: mark and
-     * space parity are not conveniently supported, and neither is
-     * DSR/DTR flow control.
-     */
-    if (!midsession || (protocol == PROT_SERIAL))
-        ser_setup_config_box(b, midsession, 0x07, 0x07);
 }
diff --git a/unix/uxser.c b/unix/uxser.c
index 31658c43..1b8d9b99 100644
--- a/unix/uxser.c
+++ b/unix/uxser.c
@@ -578,4 +578,10 @@ const BackendVtable serial_backend = {
     .id = "serial",
     .displayname = "Serial",
     .protocol = PROT_SERIAL,
+    .serial_parity_mask = ((1 << SER_PAR_NONE) |
+                           (1 << SER_PAR_ODD) |
+                           (1 << SER_PAR_EVEN)),
+    .serial_flow_mask =   ((1 << SER_FLOW_NONE) |
+                           (1 << SER_FLOW_XONXOFF) |
+                           (1 << SER_FLOW_RTSCTS)),
 };
diff --git a/windows/wincfg.c b/windows/wincfg.c
index 94c684db..fab3240f 100644
--- a/windows/wincfg.c
+++ b/windows/wincfg.c
@@ -391,12 +391,6 @@ void win_setup_config_box(struct controlbox *b, HWND *hwndp, bool has_help,
         }
     }
 
-    /*
-     * Serial back end is available on Windows.
-     */
-    if (!midsession || (protocol == PROT_SERIAL))
-        ser_setup_config_box(b, midsession, 0x1F, 0x0F);
-
     /*
      * $XAUTHORITY is not reliable on Windows, so we provide a
      * means to override it.
diff --git a/windows/winser.c b/windows/winser.c
index e0ef0475..7f3a3821 100644
--- a/windows/winser.c
+++ b/windows/winser.c
@@ -446,4 +446,13 @@ const BackendVtable serial_backend = {
     .id = "serial",
     .displayname = "Serial",
     .protocol = PROT_SERIAL,
+    .serial_parity_mask = ((1 << SER_PAR_NONE) |
+                           (1 << SER_PAR_ODD) |
+                           (1 << SER_PAR_EVEN) |
+                           (1 << SER_PAR_MARK) |
+                           (1 << SER_PAR_SPACE)),
+    .serial_flow_mask =   ((1 << SER_FLOW_NONE) |
+                           (1 << SER_FLOW_XONXOFF) |
+                           (1 << SER_FLOW_RTSCTS) |
+                           (1 << SER_FLOW_DSRDTR)),
 };