diff --git a/anymail/backends/base.py b/anymail/backends/base.py
index 0168fe12..87bbf1e2 100644
--- a/anymail/backends/base.py
+++ b/anymail/backends/base.py
@@ -462,7 +462,7 @@ def aware_datetime(self, value):
                 dt = datetime(value.year, value.month, value.day)  # naive, midnight
             else:
                 try:
-                    dt = datetime.utcfromtimestamp(value).replace(tzinfo=timezone.utc)
+                    dt = datetime.fromtimestamp(value, timezone.utc)
                 except (TypeError, ValueError):
                     return value
         if is_naive(dt):