diff --git a/.github/workflows/unit_tests.yml b/.github/workflows/unit_tests.yml
index b833369..f46b7db 100644
--- a/.github/workflows/unit_tests.yml
+++ b/.github/workflows/unit_tests.yml
@@ -15,7 +15,7 @@ jobs:
     runs-on: ubuntu-22.04
     strategy:
       matrix:
-        python-version: [3.8, 3.9, '3.10', '3.11', '3.12']
+        python-version: ['3.8', '3.9', '3.10', '3.11', '3.12']
       fail-fast: false
 
     steps:
@@ -31,6 +31,11 @@ jobs:
           pip install pytest
           pip install -r requirements.txt
 
+      - name: Backport to 3.8
+        if: matrix.python-version == '3.8'
+        run: |
+          pip install backports.zoneinfo
+
       - name: Test with pytest
         run: |
           cd tests
diff --git a/libeos/file_reader.py b/libeos/file_reader.py
index 6ab0aa9..e0a68d3 100644
--- a/libeos/file_reader.py
+++ b/libeos/file_reader.py
@@ -3,6 +3,11 @@ import os
 import subprocess
 import sys
 from datetime import datetime, timezone
+try:
+    import zoneinfo
+except ImportError:
+    # for python versions < 3.9 try to use the backports version
+    from backports import zoneinfo
 from typing import List
 
 import h5py
@@ -20,6 +25,9 @@ try:
 except Exception:
     nb_helpers = None
 
+# Time zone used to interpret time strings
+AMOR_LOCAL_TIMEZONE = zoneinfo.ZoneInfo(key='Europe/Zurich')
+
 class AmorData:
     """read meta-data and event streams from .hdf file(s), apply filters and conversions"""
     chopperDetectorDistance: float
@@ -373,7 +381,7 @@ class AmorData:
         self.pixelID_e = self.pixelID_e[filter_e]
         self.wallTime_e = self.wallTime_e[filter_e]
         if np.shape(filter_e)[0]-np.shape(self.tof_e)[0]>0.5:
-            logging.warning(f'#    strange times: {np.shape(filter_e)[0]-np.shape(self.tof_e)[0]}')
+            logging.warning(f'        strange times: {np.shape(filter_e)[0]-np.shape(self.tof_e)[0]}')
 
     def read_event_stream(self):
         self.tof_e = np.array(self.hdf['/entry1/Amor/detector/data/event_time_offset'][:])/1.e9
@@ -437,7 +445,8 @@ class AmorData:
             self.nu = self.config.nu
 
         # extract start time as unix time, adding UTC offset of 1h to time string
-        self.fileDate = datetime.fromisoformat( self.hdf['/entry1/start_time'][0].decode('utf-8')+"+01:00" )
+        dz = datetime.fromisoformat(self.hdf['/entry1/start_time'][0].decode('utf-8'))
+        self.fileDate=dz.replace(tzinfo=AMOR_LOCAL_TIMEZONE)
         self.startTime = np.int64( (self.fileDate.timestamp() ) * 1e9 )
         if self.seriesStartTime is None:
             self.seriesStartTime = self.startTime