diff --git a/tap_mailchimp/schema.py b/tap_mailchimp/schema.py
index f44f720..2296542 100644
--- a/tap_mailchimp/schema.py
+++ b/tap_mailchimp/schema.py
@@ -15,7 +15,8 @@
         'campaign_id',
         'action',
         'email_id',
-        'timestamp'
+        'timestamp',
+        '_sdc_stitch_timestamp',
     ],
     'unsubscribes': ['campaign_id', 'email_id']
 }
diff --git a/tap_mailchimp/schemas/reports_email_activity.json b/tap_mailchimp/schemas/reports_email_activity.json
index 6d4239f..df5d7df 100644
--- a/tap_mailchimp/schemas/reports_email_activity.json
+++ b/tap_mailchimp/schemas/reports_email_activity.json
@@ -48,6 +48,12 @@
       ],
       "format": "date-time"
     },
+    "_sdc_stitch_timestamp": {
+      "type": [
+        "null",
+        "string"
+      ]
+    },
     "ip": {
       "type": [
         "null",
@@ -61,4 +67,4 @@
       ]
     }
   }
-}
\ No newline at end of file
+}
diff --git a/tap_mailchimp/sync.py b/tap_mailchimp/sync.py
index fc8e063..515a650 100644
--- a/tap_mailchimp/sync.py
+++ b/tap_mailchimp/sync.py
@@ -268,6 +268,7 @@ def transform_activities(records):
                     new_activity = dict(record_template)
                     for key, value in activity.items():
                         new_activity[key] = value
+                    new_activity['_sdc_stitch_timestamp'] = str(singer.utils.now())
                     yield new_activity
 
     write_schema(catalog, stream_name)
diff --git a/tests/test_sync.py b/tests/test_sync.py
index b9e2544..a2baf65 100644
--- a/tests/test_sync.py
+++ b/tests/test_sync.py
@@ -57,7 +57,7 @@ def expected_sync_streams(self):
             'list_segment_members': {'id'},
             'list_segments': {'id'},
             'lists': {'id'},
-            'reports_email_activity': {'campaign_id', 'action', 'email_id', 'timestamp'},
+            'reports_email_activity': {'campaign_id', 'action', 'email_id', 'timestamp', '_sdc_stitch_timestamp'},
             'unsubscribes': {'campaign_id', 'email_id'}
         }