diff --git a/inkycal/modules/ical_parser.py b/inkycal/modules/ical_parser.py
index cdf6037..8a6361d 100644
--- a/inkycal/modules/ical_parser.py
+++ b/inkycal/modules/ical_parser.py
@@ -78,12 +78,12 @@ class iCalendar:
             for path in filepath:
                 with open(path, mode='r') as ical_file:
                     ical = (Calendar.from_ical(ical_file.read()))
-                    self.icalendars += ical
+                    self.icalendars.append(ical)
 
         elif isinstance(filepath, str):
             with open(filepath, mode='r') as ical_file:
                 ical = (Calendar.from_ical(ical_file.read()))
-                self.icalendars += ical
+                self.icalendars.append(ical)
         else:
             raise Exception(f"Input: '{filepath}' is not a string or list!")