diff --git a/backend/api/tests/api/test_label.py b/backend/api/tests/api/test_label.py
index 9037dd16..ada14cb0 100644
--- a/backend/api/tests/api/test_label.py
+++ b/backend/api/tests/api/test_label.py
@@ -56,7 +56,7 @@ class TestLabelCreate(APITestCase):
     def assert_create_label(self, user=None, expected_status=status.HTTP_403_FORBIDDEN):
         if user:
             self.client.force_login(user)
-        response = self.client.post(self.url, data=self.data)
+        response = self.client.post(self.url, data=self.data, format='json')
         self.assertEqual(response.status_code, expected_status)
 
     def test_allows_admin_to_create_label(self):
@@ -101,7 +101,7 @@ class TestLabelDetailAPI(APITestCase):
     def assert_update_label(self, user=None, expected_status=status.HTTP_403_FORBIDDEN):
         if user:
             self.client.force_login(user)
-        response = self.client.patch(self.url, data=self.data)
+        response = self.client.patch(self.url, data=self.data, format='json')
         self.assertEqual(response.status_code, expected_status)
         return response
 
diff --git a/backend/api/tests/api/test_project.py b/backend/api/tests/api/test_project.py
index 8650e458..17d9c4e4 100644
--- a/backend/api/tests/api/test_project.py
+++ b/backend/api/tests/api/test_project.py
@@ -45,12 +45,12 @@ class TestProjectCreate(APITestCase):
 
     def test_allow_authenticated_user_to_create_project(self):
         self.client.force_login(self.user)
-        response = self.client.post(self.url, data=self.data)
+        response = self.client.post(self.url, data=self.data, format='json')
         self.assertEqual(response.status_code, status.HTTP_201_CREATED)
         self.assertEqual(response.data['name'], self.data['name'])
 
     def test_disallow_unauthenticated_user_to_create_project(self):
-        response = self.client.post(self.url, self.data)
+        response = self.client.post(self.url, self.data, format='json')
         self.assertEqual(response.status_code, status.HTTP_403_FORBIDDEN)
 
 
@@ -76,7 +76,7 @@ class TestProjectDetailAPI(APITestCase):
 
     def assert_update_project(self, user, expected):
         self.client.force_login(user)
-        response = self.client.patch(self.url, data=self.data)
+        response = self.client.patch(self.url, data=self.data, format='json')
         self.assertEqual(response.status_code, expected)
         return response
 
diff --git a/backend/api/tests/api/test_tag.py b/backend/api/tests/api/test_tag.py
index e3c1f8d6..ca029b4d 100644
--- a/backend/api/tests/api/test_tag.py
+++ b/backend/api/tests/api/test_tag.py
@@ -43,7 +43,7 @@ class TestTagCreate(APITestCase):
     def assert_create_tag(self, user=None, expected=status.HTTP_403_FORBIDDEN):
         if user:
             self.client.force_login(user)
-        response = self.client.post(self.url, data=self.data)
+        response = self.client.post(self.url, data=self.data, format='json')
         self.assertEqual(response.status_code, expected)
         return response