diff --git a/pymisp/mispevent.py b/pymisp/mispevent.py
index 7fa77da..f374bd4 100644
--- a/pymisp/mispevent.py
+++ b/pymisp/mispevent.py
@@ -67,7 +67,7 @@ def _make_datetime(value) -> datetime:
         else:
             try:
                 # faster
-                if '+' in value or '-' in value:
+                if '+' in value or value.find('-', 10) > -1:  # date contains `-` char
                     value = datetime.strptime(value, "%Y-%m-%dT%H:%M:%S.%f%z")
                 elif '.' in value:
                     value = datetime.strptime(value, "%Y-%m-%dT%H:%M:%S.%f")
diff --git a/tests/testlive_comprehensive.py b/tests/testlive_comprehensive.py
index 3f8dc67..cd02d1b 100644
--- a/tests/testlive_comprehensive.py
+++ b/tests/testlive_comprehensive.py
@@ -2082,7 +2082,7 @@ class TestComprehensive(unittest.TestCase):
         local_tz = datetime.now(timezone.utc).astimezone().tzinfo
         event = MISPEvent()
         event.info = 'Test First Last seen'
-        event.add_attribute('ip-dst', '8.8.8.8', first_seen='2020-01-04', last_seen='2020-01-04T12:30:34.323242+8:00')
+        event.add_attribute('ip-dst', '8.8.8.8', first_seen='2020-01-04', last_seen='2020-01-04T12:30:34.323242+0800')
         obj = event.add_object(name='file', first_seen=1580147259.268763, last_seen=1580147300)
         attr = obj.add_attribute('filename', 'blah.exe')
         attr.first_seen = '2022-01-30'