diff --git a/unix/gtkapp.c b/unix/gtkapp.c
index e5cc6c6f..d7add6d1 100644
--- a/unix/gtkapp.c
+++ b/unix/gtkapp.c
@@ -192,9 +192,9 @@ static void post_initial_config_box(void *vctx, int result)
 {
     Conf *conf = (Conf *)vctx;
 
-    if (result) {
+    if (result > 0) {
         new_session_window(conf, NULL);
-    } else {
+    } else if (result == 0) {
         conf_free(conf);
         g_application_release(G_APPLICATION(app));
     }
diff --git a/unix/gtkdlg.c b/unix/gtkdlg.c
index 9e5ebf20..35973d9a 100644
--- a/unix/gtkdlg.c
+++ b/unix/gtkdlg.c
@@ -3316,8 +3316,7 @@ GtkWidget *create_config_box(const char *title, Conf *conf,
 static void dlgparam_destroy(GtkWidget *widget, gpointer data)
 {
     struct dlgparam *dp = (struct dlgparam *)data;
-    if (dp->retval >= 0)
-        dp->after(dp->afterctx, dp->retval);
+    dp->after(dp->afterctx, dp->retval);
     dlg_cleanup(dp);
     ctrl_free_box(dp->ctrlbox);
 #if GTK_CHECK_VERSION(2,0,0)
diff --git a/unix/gtkmain.c b/unix/gtkmain.c
index a70ceb5b..751a80ff 100644
--- a/unix/gtkmain.c
+++ b/unix/gtkmain.c
@@ -551,9 +551,9 @@ static void post_initial_config_box(void *vctx, int result)
         *(struct post_initial_config_box_ctx *)vctx;
     sfree(vctx);
 
-    if (result) {
+    if (result > 0) {
         new_session_window(ctx.conf, ctx.geometry_string);
-    } else {
+    } else if (result == 0) {
         /* In this main(), which only runs one session in total, a
          * negative result from the initial config box means we simply
          * terminate. */
diff --git a/unix/gtkwin.c b/unix/gtkwin.c
index 046cf09c..88b438a5 100644
--- a/unix/gtkwin.c
+++ b/unix/gtkwin.c
@@ -4016,6 +4016,13 @@ static void after_change_settings_dialog(void *vctx, int retval)
 
     sfree(vctx); /* we've copied this already */
 
+    if (retval < 0) {
+        /* If the dialog box was aborted without giving a result
+         * (probably because the whole session window closed), we have
+         * nothing further to do. */
+        return;
+    }
+
     assert(lenof(ww) == NCFGCOLOURS);
 
     inst->reconfigure_dialog = NULL;