diff --git a/app/__init__.py b/app/__init__.py
index 2db201aca..795987bd5 100644
--- a/app/__init__.py
+++ b/app/__init__.py
@@ -21,7 +21,7 @@ from flask import (
     g,
     url_for)
 from flask._compat import string_types
-from flask.globals import _lookup_req_object
+from flask.globals import _lookup_req_object, _request_ctx_stack
 from flask_login import LoginManager
 from flask_wtf import CsrfProtect
 from functools import partial
@@ -380,10 +380,10 @@ def load_user(user_id):
 
 def load_service_before_request():
     if '/static/' in request.url:
+        _request_ctx_stack.top.service = None
         return
     service_id = request.view_args.get('service_id', session.get('service_id')) if request.view_args \
         else session.get('service_id')
-    from flask.globals import _request_ctx_stack
     if _request_ctx_stack.top is not None:
         _request_ctx_stack.top.service = service_api_client.get_service(service_id)['data'] if service_id else None
 
diff --git a/tests/app/main/views/test_jobs.py b/tests/app/main/views/test_jobs.py
index 27b1d015e..0980bfcaf 100644
--- a/tests/app/main/views/test_jobs.py
+++ b/tests/app/main/views/test_jobs.py
@@ -1,4 +1,3 @@
-import csv
 import json
 import uuid
 from urllib.parse import urlparse, quote, parse_qs
@@ -7,8 +6,6 @@ import pytest
 from flask import url_for
 from bs4 import BeautifulSoup
 
-from app import utils
-from io import StringIO
 from app.main.views.jobs import get_time_left, get_status_filters
 from tests import notification_json
 from freezegun import freeze_time
@@ -117,7 +114,7 @@ def test_should_show_page_for_one_job(
         service_one['id'],
         fake_uuid,
         status=expected_api_call
-        )
+    )
 
 
 def test_get_jobs_should_tell_user_if_more_than_one_page(
@@ -262,7 +259,6 @@ def test_should_show_updates_for_one_job_as_json(
     mocker,
     fake_uuid,
 ):
-    job_json = mock_get_job(service_one['id'], fake_uuid)['data']
     response = logged_in_client.get(url_for('main.view_job_updates', service_id=service_one['id'], job_id=fake_uuid))
 
     assert response.status_code == 200
@@ -386,7 +382,6 @@ def test_should_show_notifications_for_a_service_with_next_previous(
         page=2
     ))
     assert response.status_code == 200
-    content = response.get_data(as_text=True)
     page = BeautifulSoup(response.data.decode('utf-8'), 'html.parser')
     next_page_link = page.find('a', {'rel': 'next'})
     prev_page_link = page.find('a', {'rel': 'previous'})
diff --git a/tests/app/main/views/test_service_settings.py b/tests/app/main/views/test_service_settings.py
index ad7c9663a..e55d5b9c5 100644
--- a/tests/app/main/views/test_service_settings.py
+++ b/tests/app/main/views/test_service_settings.py
@@ -88,7 +88,7 @@ def test_if_cant_send_letters_then_cant_see_letter_contact_block(
     assert 'Letter contact block' not in response.get_data(as_text=True)
 
 
-def test_letter_contact_block_shows_None_if_not_set(
+def test_letter_contact_block_shows_none_if_not_set(
     logged_in_client,
     service_one,
     mocker,
diff --git a/tests/app/main/views/test_template_history.py b/tests/app/main/views/test_template_history.py
index f851272cc..c3d06dea2 100644
--- a/tests/app/main/views/test_template_history.py
+++ b/tests/app/main/views/test_template_history.py
@@ -1,4 +1,3 @@
-import json
 from flask import url_for
 
 
@@ -54,7 +53,6 @@ def test_view_template_versions(
 ):
     service_id = fake_uuid
     template_id = fake_uuid
-    version = 1
     resp = logged_in_client.get(url_for(
         '.view_template_versions',
         service_id=service_id,
diff --git a/tests/app/test_assets.py b/tests/app/test_assets.py
index 54e0301fc..9a4c532e8 100644
--- a/tests/app/test_assets.py
+++ b/tests/app/test_assets.py
@@ -1,9 +1,10 @@
-import app
-
-
-def test_crown_logo(app_):
-    with app_.test_request_context():
-        #  This image is used by the email templates, so we should be really careful to make
-        #  sure that its always there.
-        response = app_.test_client().get('/static/images/email-template/crown-32px.gif')
+def test_crown_logo(client):
+    #  This image is used by the email templates, so we should be really careful to make
+    #  sure that its always there.
+    response = client.get('/static/images/email-template/crown-32px.gif')
     assert response.status_code == 200
+
+
+def test_static_404s_return(client):
+    response = client.get('/static/images/some-image-that-doesnt-exist.png')
+    assert response.status_code == 404
diff --git a/tests/app/test_utils.py b/tests/app/test_utils.py
index 1e7d36108..34892581f 100644
--- a/tests/app/test_utils.py
+++ b/tests/app/test_utils.py
@@ -3,7 +3,6 @@ from io import StringIO
 from csv import DictReader
 
 import pytest
-from freezegun import freeze_time
 
 from app.utils import (
     email_safe,
@@ -13,7 +12,7 @@ from app.utils import (
     Spreadsheet
 )
 
-from tests import notification_json, single_notification_json, template_json
+from tests import notification_json, single_notification_json
 
 
 def _get_notifications_csv(