diff --git a/app/models.py b/app/models.py
index 9a830652b..6678d91e6 100644
--- a/app/models.py
+++ b/app/models.py
@@ -1306,7 +1306,7 @@ class Notification(db.Model):
             serialized['line_4'] = col.get('address_line_4')
             serialized['line_5'] = col.get('address_line_5')
             serialized['line_6'] = col.get('address_line_6')
-            serialized['postcode'] = self.personalisation['postcode']
+            serialized['postcode'] = col.get('postcode')
             serialized['estimated_delivery'] = \
                 get_letter_timings(serialized['created_at'])\
                 .earliest_delivery\
diff --git a/tests/app/test_model.py b/tests/app/test_model.py
index af73e1460..a0b8d4804 100644
--- a/tests/app/test_model.py
+++ b/tests/app/test_model.py
@@ -307,3 +307,15 @@ def test_letter_notification_serializes_correctly(client, sample_letter_notifica
     assert json['line_1'] == 'test'
     assert json['line_2'] == 'London'
     assert json['postcode'] == 'N1'
+
+
+def test_letter_notification_postcode_can_be_null_for_precompiled_letters(client, sample_letter_notification):
+    sample_letter_notification.personalisation = {
+        'address_line_1': 'test',
+        'address_line_2': 'London',
+    }
+
+    json = sample_letter_notification.serialize()
+    assert json['line_1'] == 'test'
+    assert json['line_2'] == 'London'
+    assert json['postcode'] is None