diff --git a/netbox/extras/api/serializers.py b/netbox/extras/api/serializers.py
index f5e99b4434..714c925488 100644
--- a/netbox/extras/api/serializers.py
+++ b/netbox/extras/api/serializers.py
@@ -3,6 +3,7 @@
 from drf_spectacular.types import OpenApiTypes
 from drf_spectacular.utils import extend_schema_field
 from rest_framework import serializers
+from rest_framework.fields import ListField
 
 from core.api.nested_serializers import NestedDataSourceSerializer, NestedDataFileSerializer, NestedJobSerializer
 from core.api.serializers import JobSerializer
@@ -175,6 +176,12 @@ class CustomFieldChoiceSetSerializer(ValidatedModelSerializer):
         choices=CustomFieldChoiceSetBaseChoices,
         required=False
     )
+    extra_choices = serializers.ListField(
+        child=serializers.ListField(
+            min_length=2,
+            max_length=2
+        )
+    )
 
     class Meta:
         model = CustomFieldChoiceSet
diff --git a/netbox/extras/tests/test_api.py b/netbox/extras/tests/test_api.py
index 93be2d2c4b..f40372a8f7 100644
--- a/netbox/extras/tests/test_api.py
+++ b/netbox/extras/tests/test_api.py
@@ -14,7 +14,6 @@
 from extras.scripts import BooleanVar, IntegerVar, Script, StringVar
 from utilities.testing import APITestCase, APIViewTestCases
 
-
 User = get_user_model()
 
 
@@ -251,6 +250,23 @@ def setUpTestData(cls):
         )
         CustomFieldChoiceSet.objects.bulk_create(choice_sets)
 
+    def test_invalid_choice_items(self):
+        """
+        Attempting to define each choice as a single-item list should return a 400 error.
+        """
+        self.add_permissions('extras.add_customfieldchoiceset')
+        data = {
+            "name": "test",
+            "extra_choices": [
+                ["choice1"],
+                ["choice2"],
+                ["choice3"],
+            ]
+        }
+
+        response = self.client.post(self._get_list_url(), data, format='json', **self.header)
+        self.assertEqual(response.status_code, 400)
+
 
 class CustomLinkTest(APIViewTestCases.APIViewTestCase):
     model = CustomLink