diff --git a/qt/aqt/deckoptions.py b/qt/aqt/deckoptions.py
index 28600545c..634e58752 100644
--- a/qt/aqt/deckoptions.py
+++ b/qt/aqt/deckoptions.py
@@ -14,6 +14,7 @@ from aqt.qt import *
 from aqt.utils import (
     KeyboardModifiersPressed,
     addCloseShortcut,
+    ask_user_dialog,
     disable_help_button,
     restoreGeom,
     saveGeom,
@@ -33,6 +34,8 @@ class DeckOptionsDialog(QDialog):
         self.mw = mw
         self._deck = deck
         self._setup_ui()
+        self._close_event_has_cleaned_up = False
+        self._ready = False
 
     def _setup_ui(self) -> None:
         self.setWindowModality(Qt.WindowModality.ApplicationModal)
@@ -57,8 +60,44 @@ class DeckOptionsDialog(QDialog):
 
     def _on_bridge_cmd(self, cmd: str) -> None:
         if cmd == "deckOptionsReady":
+            self.ready = True
             gui_hooks.deck_options_did_load(self)
 
+    def closeEvent(self, evt: QCloseEvent) -> None:
+        if self._close_event_has_cleaned_up:
+            evt.accept()
+            return
+        evt.ignore()
+        self.if_can_close()
+
+    def _close(self):
+        """Close. Ensure the closeEvent is not ignored."""
+        self._close_event_has_cleaned_up = True
+        self.close()
+
+    def if_can_close(self):
+        """Close if there was no modification. Otherwise ask for confirmation first."""
+
+        def callbackWithUserChoice(choice: int):
+            if choice == 0:
+                # The user accepted to discard current input.
+                self._close()
+
+        def if_can_close_callback_with_data_information(has_modified_dataData: bool):
+            if has_modified_dataData:
+                ask_user_dialog(
+                    tr.card_templates_discard_changes(),
+                    callback=callbackWithUserChoice,
+                    buttons=[
+                        QMessageBox.StandardButton.Discard,
+                        (tr.adding_keep_editing(), QMessageBox.ButtonRole.RejectRole),
+                    ],
+                )
+            else:
+                self._close()
+
+        self.has_modified_data(if_can_close_callback_with_data_information)
+
     def reject(self) -> None:
         self.mw.col.set_wants_abort()
         self.web.cleanup()
@@ -66,6 +105,15 @@ class DeckOptionsDialog(QDialog):
         saveGeom(self, self.TITLE)
         QDialog.reject(self)
 
+    def has_modified_data(self, callback: Callable[[bool], None]):
+        """Calls `callback` with the information of whether any deck options are modified."""
+        if self.ready:
+            self.web.evalWithCallback(
+                "anki.deckOptionsPendingChanges()", callback
+            )
+        else:
+            callback(False)
+
 
 def confirm_deck_then_display_options(active_card: Card | None = None) -> None:
     decks = [aqt.mw.col.decks.current()]
diff --git a/ts/routes/deck-options/[deckId]/+page.svelte b/ts/routes/deck-options/[deckId]/+page.svelte
index 11af70f71..e3a5f6432 100644
--- a/ts/routes/deck-options/[deckId]/+page.svelte
+++ b/ts/routes/deck-options/[deckId]/+page.svelte
@@ -11,6 +11,10 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
     export let data: PageData;
     let page: DeckOptionsPage;
 
+    globalThis.anki ||= {};
+    globalThis.anki.deckOptionsPendingChanges = () => {
+        return data.state.isModified();
+    };
     onMount(() => {
         globalThis.$deckOptions = new Promise((resolve, _reject) => {
             resolve(page);
diff --git a/ts/routes/deck-options/lib.ts b/ts/routes/deck-options/lib.ts
index d95b1e1aa..5df94ecfb 100644
--- a/ts/routes/deck-options/lib.ts
+++ b/ts/routes/deck-options/lib.ts
@@ -292,6 +292,10 @@ export class DeckOptionsState {
         });
         return list;
     }
+
+    isModified(): boolean {
+        return this.removedConfigs.length > 0 || this.modifiedConfigs.size > 0;
+    }
 }
 
 function bytesToObject(bytes: Uint8Array): Record<string, unknown> {