diff --git a/requirements-app.txt b/requirements-app.txt
index 42fc82b9d..17b08111b 100644
--- a/requirements-app.txt
+++ b/requirements-app.txt
@@ -24,5 +24,5 @@ WTForms==2.2.1  # Pinned because of breaking change in 2.3.0
 awscli-cwlogs>=1.4,<1.5
 itsdangerous==1.1.0
 
-git+https://github.com/alphagov/notifications-utils.git@37.2.0#egg=notifications-utils==37.2.0
+git+https://github.com/alphagov/notifications-utils.git@37.3.0#egg=notifications-utils==37.3.0
 git+https://github.com/alphagov/govuk-frontend-jinja.git@v0.5.1-alpha#egg=govuk-frontend-jinja==0.5.1-alpha
diff --git a/requirements.txt b/requirements.txt
index 1b74170b0..554278870 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -26,7 +26,7 @@ WTForms==2.2.1  # Pinned because of breaking change in 2.3.0
 awscli-cwlogs>=1.4,<1.5
 itsdangerous==1.1.0
 
-git+https://github.com/alphagov/notifications-utils.git@37.2.0#egg=notifications-utils==37.2.0
+git+https://github.com/alphagov/notifications-utils.git@37.3.0#egg=notifications-utils==37.3.0
 git+https://github.com/alphagov/govuk-frontend-jinja.git@v0.5.1-alpha#egg=govuk-frontend-jinja==0.5.1-alpha
 
 ## The following requirements were added by pip freeze:
diff --git a/tests/app/main/views/test_send.py b/tests/app/main/views/test_send.py
index 89e851f11..bdb25c5e2 100644
--- a/tests/app/main/views/test_send.py
+++ b/tests/app/main/views/test_send.py
@@ -510,7 +510,7 @@ def test_upload_csv_file_with_very_long_placeholder_shows_check_page_with_errors
     mock_get_jobs,
     fake_uuid,
 ):
-    big_placeholder = ' '.join(['not ok'] * 102)
+    big_placeholder = ' '.join(['not ok'] * 402)
     mocker.patch(
         'app.main.views.send.s3download',
         return_value=f"""
@@ -4080,7 +4080,7 @@ TRIAL_MODE_MSG = (
     'Cannot send to this recipient when service is in trial mode – '
     'see https://www.notifications.service.gov.uk/trial-mode'
 )
-TOO_LONG_MSG = 'Text messages cannot be longer than 612 characters. Your message is 654 characters.'
+TOO_LONG_MSG = 'Text messages cannot be longer than 918 characters. Your message is 954 characters.'
 SERVICE_DAILY_LIMIT_MSG = 'Exceeded send limits (1000) for today'
 
 
@@ -4093,7 +4093,7 @@ SERVICE_DAILY_LIMIT_MSG = 'Exceeded send limits (1000) for today'
     (
         TOO_LONG_MSG,
         'Message too long',
-        'Text messages cannot be longer than 612 characters. Your message is 654 characters.'
+        'Text messages cannot be longer than 918 characters. Your message is 954 characters.'
     ),
     (
         SERVICE_DAILY_LIMIT_MSG,
@@ -4121,7 +4121,7 @@ def test_send_notification_shows_error_if_400(
     )
     with client_request.session_transaction() as session:
         session['recipient'] = '07700900001'
-        session['placeholders'] = {'name': 'a' * 600}
+        session['placeholders'] = {'name': 'a' * 900}
 
     page = client_request.post(
         'main.send_notification',