diff --git a/tap_marketo/__init__.py b/tap_marketo/__init__.py
index 0ecb82b..b429c6c 100644
--- a/tap_marketo/__init__.py
+++ b/tap_marketo/__init__.py
@@ -1,6 +1,8 @@
 #!/usr/bin/env python3
 
 # Marketo Docs are located at http://developers.marketo.com/rest-api/
+
+from datetime import datetime, timedelta
 import itertools
 import re
 
@@ -35,39 +37,40 @@
 
 
 ATTRIBUTION_WINDOW_README = """
-`attribution_window` may be specified by a combination of days, hours and minutes. This parameter is 
+`attribution_window` may be specified by a combination of days, hours and minutes seconds. This parameter is 
 quite useful in a moderate frequency incremental bulk extracts (e.g. once an hour)
 to allow users a way to avoid extracting all leads updated 1 day prior (i.e. default attribution window)
-examples of valid attribution_windows: 1d, 12h, 1h30m, 1d6h55m
+examples of valid attribution_windows: `1 day`, `1 days`, `2 day`, `10 days`, `10:00:00`, `1 day 05:00:00`
 """
-ATTRIBUTION_WINDOW_SPEC_RE_ATOMS = [r'\d{1,2}d', r'\d{1,2}h', r'\d{1,2}m']
-ATTRIBUTION_WINDOW_ALLOWED_RE = [
-    re.compile(''.join(x))
-    for i in range(1, 4)
-    for x in itertools.combinations(ATTRIBUTION_WINDOW_SPEC_RE_ATOMS, i)
-    ]
-
 
 def parse_attribution_window(attribution_window_string):
     f"""
     Parse optional config parameter `attribution_window`.
-
     Attribution window is used to set an earlier export_start
     for incremental replication of of the leads stream.
     
     {ATTRIBUTION_WINDOW_README}
     """
-    aw = attribution_window_string.lower().strip()
-    if not any(p.match(aw) for p in ATTRIBUTION_WINDOW_ALLOWED_RE):
-        raise ValueError(
-            f"Invalid attribution window string: {attribution_window_string}."
-            f"{ATTRIBUTION_WINDOW_README}"
-            )
-    window_code_name_map = {'d': 'days', 'h': 'hours', 'm': 'minutes'}
-    return {
-        window_code_name_map[y]: int(x)
-        for x, y in re.findall(r'(\d{1,2})([dhm])', aw)
-        }
+    errstr = f"`{attribution_window_string}` is not a valid attribution window."
+    pat = '^((?P<day>^\d+)\s+days?)?(\s+)?(?P<time>(\d{2}:\d{2}:\d{2}))?$'
+    match = re.match(pat, attribution_window_string)
+    if not match:
+        raise ValueError(errstr)
+    groups = match.groupdict()
+    delta_day = groups["day"] or '0'
+    delta_time = groups["time"] or '00:00:00'
+    try:
+        parsed_time = datetime.strptime(delta_time, '%H:%M:%S')
+        return timedelta(
+            days=int(delta_day) if delta_day else 0,
+            hours=parsed_time.hour,
+            minutes=parsed_time.minute,
+            seconds=parsed_time.second
+        )
+    except ValueError as e:
+        raise ValueError(errstr)
+    
+
 
 
 def validate_state(config, catalog, state):
diff --git a/tap_marketo/sync.py b/tap_marketo/sync.py
index 1761259..a960479 100644
--- a/tap_marketo/sync.py
+++ b/tap_marketo/sync.py
@@ -1,3 +1,5 @@
+from datetime import timedelta
+
 import csv
 import json
 import pendulum
@@ -307,8 +309,11 @@ def sync_leads(client, state, stream, config):
     initial_bookmark = pendulum.parse(bookmarks.get_bookmark(state, "leads", replication_key))
     export_start = pendulum.parse(bookmarks.get_bookmark(state, "leads", replication_key))
     if client.use_corona:
-        attribution_window = config.get('attribution_window', {'days': ATTRIBUTION_WINDOW_DAYS})
-        export_start = export_start.subtract(**attribution_window)
+        aw = config.get(
+            'attribution_window',
+            timedelta(days=ATTRIBUTION_WINDOW_DAYS)
+        )
+        export_start = export_start.subtract(days=aw.days, seconds=aw.seconds)
     
     # job_started is truncated to the microsecond 
     # in get_export_end the field export_end is also truncated to the microsecond
diff --git a/tests/test_startup.py b/tests/test_startup.py
index 9cee48f..4ce64e5 100644
--- a/tests/test_startup.py
+++ b/tests/test_startup.py
@@ -1,9 +1,10 @@
+from datetime import timedelta
 import unittest
 
 import pendulum
 import requests_mock
 
-from tap_marketo import validate_state
+from tap_marketo import validate_state, parse_attribution_window
 from tap_marketo.sync import determine_replication_key
 
 class TestValidateState(unittest.TestCase):
@@ -268,3 +269,29 @@ def test_validate_state(self):
 
         self.assertDictEqual(validate_state(mock_config, mock_catalog, mock_state_2),
                              expected_state_2)
+
+    def test_parse_attribution_window_parses(self):
+        """Verify attribution window is successfully parsed for valid patterns."""
+        
+        aw1 = '3 day 20:00:00'
+        aw2 = '1 days'
+        aw3 = '10:10:10'
+        res1 = parse_attribution_window(aw1)
+        res2 = parse_attribution_window(aw2)
+        res3 = parse_attribution_window(aw3)
+        assert res1 == timedelta(days=3, hours=20)
+        assert res2 == timedelta(days=1)
+        assert res3 == timedelta(hours=10, minutes=10, seconds=10)
+
+    def test_parse_attribution_window_raises(self):
+        """Verify parse_attribution_window raised ValueError for invalid patterns."""
+
+        aw1 = 'foobar 3 day 20:00:00'
+        aw2 = '3 day 1:00:00'
+        aw3 = '10:00:00 foobar'
+        with self.assertRaises(ValueError):
+            parse_attribution_window(aw1)        
+        with self.assertRaises(ValueError):
+            parse_attribution_window(aw2)
+        with self.assertRaises(ValueError):
+            parse_attribution_window(aw3)
\ No newline at end of file