diff --git a/src/aare/gui/widgets/popout_window.py b/src/aare/gui/widgets/popout_window.py
index 40fd96b9..e615bbfc 100644
--- a/src/aare/gui/widgets/popout_window.py
+++ b/src/aare/gui/widgets/popout_window.py
@@ -196,7 +196,9 @@ class PopoutWindow(QWidget):
         super().mousePressEvent(event)
 
     def mouseMoveEvent(self, event):
-        if self._manual_edges and self._press_global is not None:
+        # Both press fields are set together in mousePressEvent; the second
+        # check exists for the pyright gate, which can't see that pairing.
+        if self._manual_edges and self._press_global is not None and self._press_geom is not None:
             delta = event.globalPosition().toPoint() - self._press_global
             geom = QRect(self._press_geom)
             if self._manual_edges & Qt.Edge.LeftEdge: