diff --git a/LICENSE b/LICENSE
index 4659f8b..bde9e53 100644
--- a/LICENSE
+++ b/LICENSE
@@ -1,6 +1,6 @@
 The MIT License (MIT)
 
-Copyright (c) 2016-2020 Florian Pigorsch & Contributors
+Copyright (c) 2016-2021 Florian Pigorsch & Contributors
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
diff --git a/README.md b/README.md
index 867343a..61e2035 100644
--- a/README.md
+++ b/README.md
@@ -229,6 +229,6 @@ E.g. use [Poedit](https://poedit.net/) or [Localise Online Editor](https://local
 `msgfmt gpxposter.po -o gpxposter.mo`
 
 ## License
-[MIT](https://github.com/flopp/GpxTrackPoster/blob/master/LICENSE) © 2016-2020 Florian Pigorsch
+[MIT](https://github.com/flopp/GpxTrackPoster/blob/master/LICENSE) © 2016-2021 Florian Pigorsch
 
 [strava-activity-type]: https://developers.strava.com/docs/reference/#api-models-ActivityType
diff --git a/gpxtrackposter/calendar_drawer.py b/gpxtrackposter/calendar_drawer.py
index 08b360b..ac28832 100644
--- a/gpxtrackposter/calendar_drawer.py
+++ b/gpxtrackposter/calendar_drawer.py
@@ -1,5 +1,5 @@
 """Draw a calendar poster."""
-# Copyright 2016-2020 Florian Pigorsch & Contributors. All rights reserved.
+# Copyright 2016-2021 Florian Pigorsch & Contributors. All rights reserved.
 #
 # Use of this source code is governed by a MIT-style
 # license that can be found in the LICENSE file.
diff --git a/gpxtrackposter/circular_drawer.py b/gpxtrackposter/circular_drawer.py
index 65234b2..3693fa9 100644
--- a/gpxtrackposter/circular_drawer.py
+++ b/gpxtrackposter/circular_drawer.py
@@ -1,5 +1,5 @@
 """Draw a circular Poster."""
-# Copyright 2016-2020 Florian Pigorsch & Contributors. All rights reserved.
+# Copyright 2016-2021 Florian Pigorsch & Contributors. All rights reserved.
 #
 # Use of this source code is governed by a MIT-style
 # license that can be found in the LICENSE file.
diff --git a/gpxtrackposter/cli.py b/gpxtrackposter/cli.py
index 743d217..4243cd3 100755
--- a/gpxtrackposter/cli.py
+++ b/gpxtrackposter/cli.py
@@ -1,6 +1,6 @@
 #!/usr/bin/env python
 
-# Copyright 2016-2020 Florian Pigorsch & Contributors. All rights reserved.
+# Copyright 2016-2021 Florian Pigorsch & Contributors. All rights reserved.
 #
 # Use of this source code is governed by a MIT-style
 # license that can be found in the LICENSE file.
diff --git a/gpxtrackposter/exceptions.py b/gpxtrackposter/exceptions.py
index 7a70183..304ca1c 100644
--- a/gpxtrackposter/exceptions.py
+++ b/gpxtrackposter/exceptions.py
@@ -1,4 +1,4 @@
-# Copyright 2016-2020 Florian Pigorsch & Contributors. All rights reserved.
+# Copyright 2016-2021 Florian Pigorsch & Contributors. All rights reserved.
 #
 # Use of this source code is governed by a MIT-style
 # license that can be found in the LICENSE file.
diff --git a/gpxtrackposter/github_drawer.py b/gpxtrackposter/github_drawer.py
index 828201f..0e2e3d2 100644
--- a/gpxtrackposter/github_drawer.py
+++ b/gpxtrackposter/github_drawer.py
@@ -1,4 +1,4 @@
-# Copyright 2020 Florian Pigorsch & Contributors. All rights reserved.
+# Copyright 2020-2021 Florian Pigorsch & Contributors. All rights reserved.
 #
 # Use of this source code is governed by a MIT-style
 # license that can be found in the LICENSE file.
diff --git a/gpxtrackposter/grid_drawer.py b/gpxtrackposter/grid_drawer.py
index 07b0fc8..f9ac8b3 100644
--- a/gpxtrackposter/grid_drawer.py
+++ b/gpxtrackposter/grid_drawer.py
@@ -1,5 +1,5 @@
 """Draw a grid poster."""
-# Copyright 2016-2020 Florian Pigorsch & Contributors. All rights reserved.
+# Copyright 2016-2021 Florian Pigorsch & Contributors. All rights reserved.
 #
 # Use of this source code is governed by a MIT-style
 # license that can be found in the LICENSE file.
diff --git a/gpxtrackposter/heatmap_drawer.py b/gpxtrackposter/heatmap_drawer.py
index d556d62..205823f 100644
--- a/gpxtrackposter/heatmap_drawer.py
+++ b/gpxtrackposter/heatmap_drawer.py
@@ -1,5 +1,5 @@
 """Draw a heatmap poster."""
-# Copyright 2016-2020 Florian Pigorsch & Contributors. All rights reserved.
+# Copyright 2016-2021 Florian Pigorsch & Contributors. All rights reserved.
 #
 # Use of this source code is governed by a MIT-style
 # license that can be found in the LICENSE file.
diff --git a/gpxtrackposter/localization.py b/gpxtrackposter/localization.py
index 60a20a8..676ab32 100644
--- a/gpxtrackposter/localization.py
+++ b/gpxtrackposter/localization.py
@@ -1,4 +1,4 @@
-# Copyright 2016-2020 Florian Pigorsch & Contributors. All rights reserved.
+# Copyright 2016-2021 Florian Pigorsch & Contributors. All rights reserved.
 #
 # Use of this source code is governed by a MIT-style
 # license that can be found in the LICENSE file.
diff --git a/gpxtrackposter/poster.py b/gpxtrackposter/poster.py
index e2dab68..1c1a4bf 100644
--- a/gpxtrackposter/poster.py
+++ b/gpxtrackposter/poster.py
@@ -1,5 +1,5 @@
 """Create a poster from track data."""
-# Copyright 2016-2020 Florian Pigorsch & Contributors. All rights reserved.
+# Copyright 2016-2021 Florian Pigorsch & Contributors. All rights reserved.
 #
 # Use of this source code is governed by a MIT-style
 # license that can be found in the LICENSE file.
diff --git a/gpxtrackposter/quantity_range.py b/gpxtrackposter/quantity_range.py
index cb400bd..e1d1c1f 100644
--- a/gpxtrackposter/quantity_range.py
+++ b/gpxtrackposter/quantity_range.py
@@ -1,4 +1,4 @@
-# Copyright 2016-2020 Florian Pigorsch & Contributors. All rights reserved.
+# Copyright 2016-2021 Florian Pigorsch & Contributors. All rights reserved.
 #
 # Use of this source code is governed by a MIT-style
 # license that can be found in the LICENSE file.
diff --git a/gpxtrackposter/timezone_adjuster.py b/gpxtrackposter/timezone_adjuster.py
index a3eb67e..9dde750 100644
--- a/gpxtrackposter/timezone_adjuster.py
+++ b/gpxtrackposter/timezone_adjuster.py
@@ -1,4 +1,4 @@
-# Copyright 2016-2020 Florian Pigorsch & Contributors. All rights reserved.
+# Copyright 2016-2021 Florian Pigorsch & Contributors. All rights reserved.
 #
 # Use of this source code is governed by a MIT-style
 # license that can be found in the LICENSE file.
@@ -24,9 +24,8 @@ def adjust(cls, time: datetime.datetime, latlng: s2sphere.LatLng) -> datetime.da
         if time.utcoffset():
             return time
         assert cls._timezonefinder
-        tz_name = cls._timezonefinder.timezone_at(lat=latlng.lat().degrees, lng=latlng.lng().degrees)
-        if tz_name is None:
-            return time
+        # if tz_name name is None set it to UTC
+        tz_name = cls._timezonefinder.timezone_at(lat=latlng.lat().degrees, lng=latlng.lng().degrees) or "UTC"
         tz = pytz.timezone(tz_name)
         tz_time = time.astimezone(tz)
         return tz_time
diff --git a/gpxtrackposter/track.py b/gpxtrackposter/track.py
index 6404941..85ff0a4 100644
--- a/gpxtrackposter/track.py
+++ b/gpxtrackposter/track.py
@@ -1,5 +1,5 @@
 """Create and maintain info about a given activity track (corresponding to one GPX file)."""
-# Copyright 2016-2020 Florian Pigorsch & Contributors. All rights reserved.
+# Copyright 2016-2021 Florian Pigorsch & Contributors. All rights reserved.
 #
 # Use of this source code is governed by a MIT-style
 # license that can be found in the LICENSE file.
diff --git a/gpxtrackposter/track_loader.py b/gpxtrackposter/track_loader.py
index dbd4caa..da8da94 100644
--- a/gpxtrackposter/track_loader.py
+++ b/gpxtrackposter/track_loader.py
@@ -1,7 +1,7 @@
 """Handle parsing of GPX files and writing/loading of cached data"""
 
 
-# Copyright 2016-2020 Florian Pigorsch & Contributors. All rights reserved.
+# Copyright 2016-2021 Florian Pigorsch & Contributors. All rights reserved.
 #
 # Use of this source code is governed by a MIT-style
 # license that can be found in the LICENSE file.
diff --git a/gpxtrackposter/tracks_drawer.py b/gpxtrackposter/tracks_drawer.py
index ac1bfbc..c93e9af 100644
--- a/gpxtrackposter/tracks_drawer.py
+++ b/gpxtrackposter/tracks_drawer.py
@@ -1,5 +1,5 @@
 """Contains the base class TracksDrawer, which other Drawers inherit from."""
-# Copyright 2016-2020 Florian Pigorsch & Contributors. All rights reserved.
+# Copyright 2016-2021 Florian Pigorsch & Contributors. All rights reserved.
 #
 # Use of this source code is governed by a MIT-style
 # license that can be found in the LICENSE file.
diff --git a/gpxtrackposter/units.py b/gpxtrackposter/units.py
index c48a91f..1b5b520 100644
--- a/gpxtrackposter/units.py
+++ b/gpxtrackposter/units.py
@@ -1,4 +1,4 @@
-# Copyright 2016-2020 Florian Pigorsch & Contributors. All rights reserved.
+# Copyright 2016-2021 Florian Pigorsch & Contributors. All rights reserved.
 #
 # Use of this source code is governed by a MIT-style
 # license that can be found in the LICENSE file.
diff --git a/gpxtrackposter/utils.py b/gpxtrackposter/utils.py
index 1bc1074..7d1b606 100644
--- a/gpxtrackposter/utils.py
+++ b/gpxtrackposter/utils.py
@@ -1,5 +1,5 @@
 """Assorted utility methods for use in creating posters."""
-# Copyright 2016-2020 Florian Pigorsch & Contributors. All rights reserved.
+# Copyright 2016-2021 Florian Pigorsch & Contributors. All rights reserved.
 #
 # Use of this source code is governed by a MIT-style
 # license that can be found in the LICENSE file.
diff --git a/gpxtrackposter/value_range.py b/gpxtrackposter/value_range.py
index 4f01b81..077b6dd 100644
--- a/gpxtrackposter/value_range.py
+++ b/gpxtrackposter/value_range.py
@@ -1,5 +1,5 @@
 """Represent a range of numerical values"""
-# Copyright 2016-2020 Florian Pigorsch & Contributors. All rights reserved.
+# Copyright 2016-2021 Florian Pigorsch & Contributors. All rights reserved.
 #
 # Use of this source code is governed by a MIT-style
 # license that can be found in the LICENSE file.
diff --git a/gpxtrackposter/xy.py b/gpxtrackposter/xy.py
index e3d418c..9712fce 100644
--- a/gpxtrackposter/xy.py
+++ b/gpxtrackposter/xy.py
@@ -1,5 +1,5 @@
 """Represent x,y coords with properly overloaded operations."""
-# Copyright 2016-2020 Florian Pigorsch & Contributors. All rights reserved.
+# Copyright 2016-2021 Florian Pigorsch & Contributors. All rights reserved.
 #
 # Use of this source code is governed by a MIT-style
 # license that can be found in the LICENSE file.
diff --git a/gpxtrackposter/year_range.py b/gpxtrackposter/year_range.py
index fca3394..fd7c602 100644
--- a/gpxtrackposter/year_range.py
+++ b/gpxtrackposter/year_range.py
@@ -1,5 +1,5 @@
 """Represent a range of years, with ability to update based on a track"""
-# Copyright 2016-2020 Florian Pigorsch & Contributors. All rights reserved.
+# Copyright 2016-2021 Florian Pigorsch & Contributors. All rights reserved.
 #
 # Use of this source code is governed by a MIT-style
 # license that can be found in the LICENSE file.
diff --git a/scripts/bump_year.py b/scripts/bump_year.py
index ab809a9..284e542 100755
--- a/scripts/bump_year.py
+++ b/scripts/bump_year.py
@@ -1,6 +1,6 @@
 #!/usr/bin/env python
 
-# Copyright 2018-2020 Florian Pigorsch & Contributors. All rights reserved.
+# Copyright 2018-2021 Florian Pigorsch & Contributors. All rights reserved.
 #
 # Use of this source code is governed by a MIT-style
 # license that can be found in the LICENSE file.
diff --git a/scripts/check_copyright.py b/scripts/check_copyright.py
index d605eab..1c7e1e4 100755
--- a/scripts/check_copyright.py
+++ b/scripts/check_copyright.py
@@ -1,6 +1,6 @@
 #!/usr/bin/env python
 
-# Copyright 2018-2020 Florian Pigorsch & Contributors. All rights reserved.
+# Copyright 2018-2021 Florian Pigorsch & Contributors. All rights reserved.
 #
 # Use of this source code is governed by a MIT-style
 # license that can be found in the LICENSE file.
@@ -40,7 +40,7 @@ def has_valid_copyright(file_name: str) -> bool:
     return ok
 
 
-if not all([has_valid_copyright(file_name) for file_name in sys.argv]):
+if not all(has_valid_copyright(file_name) for file_name in sys.argv):
     sys.exit(1)
 
 sys.exit(0)
diff --git a/scripts/update_readme.py b/scripts/update_readme.py
index 2d7a61b..268d57e 100755
--- a/scripts/update_readme.py
+++ b/scripts/update_readme.py
@@ -1,6 +1,6 @@
 #!/usr/bin/env python
 
-# Copyright 2018-2020 Florian Pigorsch & Contributors. All rights reserved.
+# Copyright 2018-2021 Florian Pigorsch & Contributors. All rights reserved.
 #
 # Use of this source code is governed by a MIT-style
 # license that can be found in the LICENSE file.
diff --git a/tests/test_timezone_adjuster.py b/tests/test_timezone_adjuster.py
index 30f46ad..b1c777f 100644
--- a/tests/test_timezone_adjuster.py
+++ b/tests/test_timezone_adjuster.py
@@ -1,4 +1,4 @@
-# Copyright 2020 Florian Pigorsch & Contributors. All rights reserved.
+# Copyright 2020-2021 Florian Pigorsch & Contributors. All rights reserved.
 #
 # Use of this source code is governed by a MIT-style
 # license that can be found in the LICENSE file.
diff --git a/tests/test_utils.py b/tests/test_utils.py
index a165846..5ff48ce 100644
--- a/tests/test_utils.py
+++ b/tests/test_utils.py
@@ -1,4 +1,4 @@
-# Copyright 2018-2020 Florian Pigorsch & Contributors. All rights reserved.
+# Copyright 2018-2021 Florian Pigorsch & Contributors. All rights reserved.
 #
 # Use of this source code is governed by a MIT-style
 # license that can be found in the LICENSE file.