diff --git a/src/clip_annotator/annotator.py b/src/clip_annotator/annotator.py
index ac37da5..91c2bbd 100644
--- a/src/clip_annotator/annotator.py
+++ b/src/clip_annotator/annotator.py
@@ -148,6 +148,15 @@ class Annotator(QMainWindow):
             return None
         return self._json_read(meta_path)
 
+    # ── helpers ────────────────────────────────────────────────────
+    def _update_window_title(self):
+        total = len(self.selector.clips)
+        try:
+            idx = self.selector.clips.index(self.filename) + 1
+        except ValueError:
+            idx = "?"
+        self.setWindowTitle(f"Clip Annotator ({idx} / {total})")
+
     # ── UI setup ───────────────────────────────────────────────────
     def _init_ui(self):
         self.mc = MaskCanvas(self.frames, self.dh, self.dw)
@@ -265,6 +274,8 @@ class Annotator(QMainWindow):
             self._set_answers(self._pending_answers)
             self._pending_answers = None
 
+        self._update_window_title()
+
     def _build_question_panel(self) -> QVBoxLayout:
         vbox = QVBoxLayout()
         for section, qs in self.cfg.get_questions():
@@ -409,6 +420,7 @@ class Annotator(QMainWindow):
             self._set_answers(self._pending_answers)
             self._pending_answers = None
         self.btn_prev.setEnabled(self.history_pos > 0)
+        self._update_window_title()
 
     def _advance_clip(self):
         if self.history_pos < len(self.history) - 1: