diff --git a/asammdf/gui/widgets/plot.py b/asammdf/gui/widgets/plot.py
index <HASH>..<HASH> 100644
--- a/asammdf/gui/widgets/plot.py
+++ b/asammdf/gui/widgets/plot.py
@@ -1287,9 +1287,9 @@ class _Plot(pg.PlotWidget):
                 dlg.setModal(True)
                 dlg.exec_()
                 sig = dlg.result
-                sig.uuid = uuid4()
 
                 if sig is not None:
+                    sig.uuid = uuid4()
                     self.add_new_channels([sig], computed=True)
                     self.computation_channel_inserted.emit()
 
diff --git a/asammdf/version.py b/asammdf/version.py
index <HASH>..<HASH> 100644
--- a/asammdf/version.py
+++ b/asammdf/version.py
@@ -1,4 +1,4 @@
 # -*- coding: utf-8 -*-

 """ asammdf version module """

 

-__version__ = "5.13.7"

+__version__ = "5.13.8"
release <I>
fix error when canceling a computation channel window