diff --git a/bec_widgets/widgets/plots/waveform/waveform.py b/bec_widgets/widgets/plots/waveform/waveform.py
index 94cf8d5e..e22c3b3a 100644
--- a/bec_widgets/widgets/plots/waveform/waveform.py
+++ b/bec_widgets/widgets/plots/waveform/waveform.py
@@ -467,6 +467,8 @@ class Waveform(PlotBase):
         """
         Slot for when the scan history dialog is closed.
         """
+        if self.scan_history_dialog is None:
+            return
         self.scan_history_widget.close()
         self.scan_history_widget.deleteLater()
         self.scan_history_dialog.deleteLater()