diff --git a/QtPyLoT.py b/QtPyLoT.py
index f32c19b7..b1e132f8 100755
--- a/QtPyLoT.py
+++ b/QtPyLoT.py
@@ -716,7 +716,7 @@ class MainWindow(QMainWindow):
             event = self.get_current_event()
         data = Data(self, event)
         try:
-            data_new = Data(self, evtdata=fname)
+            data_new = Data(self, evtdata=str(fname))
             data += data_new
         except ValueError:
             qmb = QMessageBox(self, icon=QMessageBox.Question,
diff --git a/pylot/core/io/data.py b/pylot/core/io/data.py
index 21488ce5..343eb778 100644
--- a/pylot/core/io/data.py
+++ b/pylot/core/io/data.py
@@ -39,7 +39,7 @@ class Data(object):
         elif isinstance(evtdata, dict):
             evt = readPILOTEvent(**evtdata)
             evtdata = evt
-        elif isinstance(evtdata, basestring):
+        elif isinstance(evtdata, str):
             try:
                 cat = read_events(evtdata)
                 if len(cat) is not 1: