diff --git a/airflow_plugins/operators/sensors/file_sensor.py b/airflow_plugins/operators/sensors/file_sensor.py
index 98ea4f8..cf25b74 100644
--- a/airflow_plugins/operators/sensors/file_sensor.py
+++ b/airflow_plugins/operators/sensors/file_sensor.py
@@ -3,6 +3,7 @@
 import time
 from datetime import datetime, timedelta
 
+import pytz
 from airflow.exceptions import (
     AirflowException,
     AirflowSensorTimeout,
@@ -12,6 +13,7 @@
 from airflow.operators.sensors import BaseSensorOperator
 from airflow.utils.decorators import apply_defaults
 from pytz import timezone
+from pytz.exceptions import UnknownTimeZoneError
 
 from airflow_plugins.hooks import FTPHook
 from airflow_plugins.operators import FileOperator
@@ -66,7 +68,14 @@ def _send_notification(self, context, success=False):
             send_notification(ti.get_dagrun(), text, title, color)
             return
 
-        runtime = datetime.now() - ti.start_date
+        try:
+            tz = timezone(ti.start_date.tm_zone)
+        except (AttributeError, UnknownTimeZoneError):  # tm_zone not set on t
+            runtime = datetime.now() - ti.start_date
+        else:
+            runtime = datetime.utcnow().replace(
+                tzinfo=ti.tm_zone) - ti.start_date
+
         if runtime >= self.notify_after:
             if (self.last_notification is None or
                     runtime >= self.last_notification + self.notify_delta):
@@ -149,6 +158,7 @@ def execute(self, context):
             # notify about success in case of previous warnings
             self._send_notification(context, success=True)
         logging.info('Success criteria met. Exiting.')
+        self._send_notification(context, success=False)
         return poke_result
 
     def poke(self, context):
@@ -196,6 +206,10 @@ def poke(self, context):
 
             def get_last_modified(fileobj):
                 timestamp = fileobj.last_modified
+
+                if isinstance(timestamp, datetime):
+                    return timestamp
+
                 tformat = '%a, %d %b %Y %H:%M:%S %Z'
                 dt = datetime.strptime(timestamp, tformat)
                 t = time.strptime(timestamp, tformat)
diff --git a/tests/operators/sensors/test_file_sensor.py b/tests/operators/sensors/test_file_sensor.py
index d252ecf..3d6899c 100644
--- a/tests/operators/sensors/test_file_sensor.py
+++ b/tests/operators/sensors/test_file_sensor.py
@@ -1,10 +1,10 @@
 from datetime import datetime, timedelta
 from time import sleep
 
-import boto
+import boto3
 import pytest
 from airflow.exceptions import AirflowException
-from boto.s3.key import Key
+# from boto3.s3.key import Key
 from mock import Mock
 from moto import mock_s3
 
@@ -46,13 +46,14 @@ def test_files_sensor_fail_on_unsupported_connection():
 
 @mock_s3
 def test_files_on_s3():
-    conn = boto.connect_s3()
-    bucket = conn.create_bucket('storiesbi-datapipeline')
+    conn = boto3.resource('s3')
+    conn.create_bucket(Bucket='storiesbi-datapipeline')
+
     get_or_update_conn("s3.stories.bi", conn_type="s3")
 
     file_sensor = FileSensor(
         task_id="check_new_file",
-        path="foo",
+        path="ss://storiesbi-datapipeline/foo",
         conn_id="s3.stories.bi",
         modified="anytime"
     )
@@ -61,27 +62,22 @@ def test_files_on_s3():
 
     assert not file_sensor.poke(ctx)
 
-    k = Key(bucket)
-    k.key = "foo"
-    k.set_contents_from_string("bar")
+    conn.Object('storiesbi-datapipeline', 'foo').put(Body="bar")
 
     assert file_sensor.poke(ctx)
 
 
 @mock_s3
 def test_files_on_s3_modified_after():
-    conn = boto.connect_s3()
-    bucket = conn.create_bucket('storiesbi-datapipeline')
-
-    k = Key(bucket)
-    k.key = "foo"
-    k.set_contents_from_string("bar")
+    conn = boto3.resource('s3')
+    conn.create_bucket(Bucket='storiesbi-datapipeline')
+    conn.Object('storiesbi-datapipeline', 'foo').put(Body="bar")
 
     get_or_update_conn("s3.stories.bi", conn_type="s3")
 
     file_sensor = FileSensor(
         task_id="check_new_file",
-        path="foo",
+        path="s3://storiesbi-datapipeline/foo",
         conn_id="s3.stories.bi",
         modified=datetime.now()
     )
@@ -92,19 +88,16 @@ def test_files_on_s3_modified_after():
 
     # Hacky hacky!
     sleep(1)
-    key = bucket.get_key("foo")
-    key.set_contents_from_string("baz")
+    conn.Object('storiesbi-datapipeline', 'foo').put(Body="baz")
 
     assert file_sensor.poke(ctx)
 
 
 @mock_s3
 def test_files_on_s3_from_custom_bucket_defined_in_path():
-    conn = boto.connect_s3()
-    bucket = conn.create_bucket('testing')
-    k = Key(bucket)
-    k.key = "foo"
-    k.set_contents_from_string("baz")
+    conn = boto3.resource('s3')
+    conn.create_bucket(Bucket='testing')
+    conn.Object('testing', 'foo').put(Body="baz")
 
     get_or_update_conn("s3.stories.bi", conn_type="s3")
     yesterday = datetime.now() - timedelta(1)
@@ -119,3 +112,22 @@ def test_files_on_s3_from_custom_bucket_defined_in_path():
     file_sensor.pre_execute(ctx)
 
     assert file_sensor.poke(ctx)
+
+
+@mock_s3
+def test_operator_notification():
+    conn = boto3.resource('s3')
+    conn.create_bucket(Bucket='testing')
+    conn.Object('testing', 'foo').put(Body="baz")
+
+    get_or_update_conn("s3.stories.bi", conn_type="s3")
+    yesterday = datetime.now() - timedelta(1)
+
+    file_sensor = FileSensor(
+        task_id="check_new_file",
+        path="s3://testing/foo",
+        conn_id="s3.stories.bi",
+        modified=yesterday
+    )
+
+    file_sensor._send_notification(ctx, success=False)