diff --git a/django_select2/conf.py b/django_select2/conf.py
index 8862932a..a3117014 100644
--- a/django_select2/conf.py
+++ b/django_select2/conf.py
@@ -198,6 +198,14 @@ class Select2Conf(AppConf):
     ``settings.DJANGO_SELECT2_I18N`` refers to :attr:`.I18N_PATH`.
     """
 
+    JSON_ENCODER = 'django.core.serializers.json.DjangoJSONEncoder'
+    """
+    A :class:`JSONEncoder<json.JSONEncoder>` used to generate the API response for the model widgets.
+
+    A custom JSON encoder might be useful when your models uses
+    a special primary key, that isn't serializable by the default encoder.
+    """
+
     class Meta:
         """Prefix for all Django-Select2 settings."""
 
diff --git a/django_select2/views.py b/django_select2/views.py
index c03f683e..0af69b64 100644
--- a/django_select2/views.py
+++ b/django_select2/views.py
@@ -3,6 +3,7 @@
 from django.core.signing import BadSignature
 from django.http import Http404, JsonResponse
 from django.views.generic.list import BaseListView
+from django.utils.module_loading import import_string
 
 from .cache import cache
 from .conf import settings
@@ -43,7 +44,8 @@ def get(self, request, *args, **kwargs):
                     for obj in context["object_list"]
                 ],
                 "more": context["page_obj"].has_next(),
-            }
+            },
+            encoder=import_string(settings.SELECT2_JSON_ENCODER)
         )
 
     def get_queryset(self):