diff --git a/HISTORY.rst b/HISTORY.rst
index c9d0094..85bdbac 100644
--- a/HISTORY.rst
+++ b/HISTORY.rst
@@ -10,6 +10,7 @@ History
 * Forked and rebranded into ``django-commentary``.
 * Dropped support for Python<3.6 and Django<3.0.
 * Added the ``delete_stale_comments`` management command.
+* Added db_index to ``object_pk`` and ``is_removed`` fields.
 
 1.9.1 (2019-02-20)
 ------------------
diff --git a/commentary/abstracts.py b/commentary/abstracts.py
index 593f0d0..e75f4e4 100644
--- a/commentary/abstracts.py
+++ b/commentary/abstracts.py
@@ -26,7 +26,7 @@ class BaseCommentAbstractModel(models.Model):
         ContentType, verbose_name=_('content type'),
         related_name='content_type_set_for_%(class)s', on_delete=models.CASCADE
     )
-    object_pk = models.CharField(_('object ID'), max_length=255)
+    object_pk = models.CharField(_('object ID'), max_length=64, db_index=True)
     content_object = GenericForeignKey(
         ct_field='content_type', fk_field='object_pk'
     )
@@ -43,7 +43,7 @@ class BaseCommentAbstractModel(models.Model):
         )
     )
     is_removed = models.BooleanField(
-        _('is removed'), default=False, help_text=_(
+        _('is removed'), default=False, db_index=True, help_text=_(
             'Check this box if the comment is inappropriate. A "This '
             'comment has been removed" message will be displayed instead.'
         )
diff --git a/commentary/migrations/0005_add_db_indexes.py b/commentary/migrations/0005_add_db_indexes.py
new file mode 100644
index 0000000..d956f0a
--- /dev/null
+++ b/commentary/migrations/0005_add_db_indexes.py
@@ -0,0 +1,34 @@
+from django.conf import settings
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        migrations.swappable_dependency(settings.AUTH_USER_MODEL),
+        ('commentary', '0004_commentary'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='comment',
+            name='is_removed',
+            field=models.BooleanField(
+                db_index=True, default=False, help_text=(
+                    'Check this box if the comment is inappropriate.'
+                    ' A "This comment has been removed" message'
+                    ' will be displayed instead.'
+                ), verbose_name='is removed'),
+        ),
+        migrations.AlterField(
+            model_name='comment',
+            name='object_pk',
+            field=models.CharField(
+                db_index=True, max_length=64, verbose_name='object ID'
+            ),
+        ),
+        migrations.AlterUniqueTogether(
+            name='commentflag',
+            unique_together={('user', 'comment', 'flag')},
+        ),
+    ]
diff --git a/docs/models.txt b/docs/models.txt
index d385caf..eb40a55 100644
--- a/docs/models.txt
+++ b/docs/models.txt
@@ -28,8 +28,8 @@ The comment models
 
     .. attribute:: object_pk
 
-        A :class:`~django.db.models.TextField` containing the primary
-        key of the object the comment is attached to.
+        A :class:`~django.db.models.CharField` containing the primary
+        key of the object the comment is attached to. ``max_length=64``.
 
     .. attribute:: site