diff --git a/src/ui_signals.cpp b/src/ui_signals.cpp
index 01b9bc9..994b864 100644
--- a/src/ui_signals.cpp
+++ b/src/ui_signals.cpp
@@ -24,6 +24,15 @@ void on_signal_switch(GObject* obj, GParamSpec*, gpointer user) {
     const std::vector<SignalInfo>& signals = app->model->signals();
     if (index < signals.size()) name = signals[index].name;
   }
+  // Hold a reference on the emitting widget across the rebuild.  `rebuild_signal_panels` destroys
+  // the list that owns `obj` (this check button's row), dropping the row's reference and leaving
+  // only GLib's own per-emission ref.  `gtk_check_button_set_active` emits both `notify::active`
+  // and `toggled` in sequence: GLib's ref covers only one emission at a time, so after
+  // `notify::active` finishes GLib unrefs the instance and, without our extra hold, that is the
+  // last reference -- and the subsequent `toggled` emission is then into freed memory, which is
+  // the two `GLib-GObject-CRITICAL` diagnostics.  Taking our own ref here and releasing it from
+  // an idle keeps the instance alive until after `set_active` has emitted everything and returned.
+  g_object_ref(obj);
   app->model->set_signal_enabled(index, on);
   if (!on) {
     // A trace of a signal nobody acquires draws nothing, and holds the slot a live one could take.
@@ -48,6 +57,11 @@ void on_signal_switch(GObject* obj, GParamSpec*, gpointer user) {
   }
   // The enable state is part of the session (a signal can be on only as a math channel's source).
   schedule_layout_save(*app);
+  // Release the extra reference from an idle so that `set_active`'s full emission chain --
+  // `notify::active` and `toggled` -- has completed before the instance can be finalized.
+  g_idle_add_full(G_PRIORITY_DEFAULT_IDLE,
+                  +[](gpointer) -> gboolean { return G_SOURCE_REMOVE; },
+                  obj, g_object_unref);
 }
 
 /// The palette entry a signal owns: its position among the *plottable* signals, the