diff --git a/django_kepi/activity_model.py b/django_kepi/activity_model.py
index b7163c2..468abef 100644
--- a/django_kepi/activity_model.py
+++ b/django_kepi/activity_model.py
@@ -79,9 +79,6 @@ class Activity(models.Model):
             blank=True,
             )
 
-    other_fields = models.TextField(
-            )
-
     active = models.BooleanField(
             default=True,
             )
@@ -133,8 +130,8 @@ class Activity(models.Model):
             if value is not None:
                 result[fieldname] = value
 
-        for f,v in json.loads(self.other_fields).items():
-            result[f] = v
+        for f in ActivityFields.objects.filter(parent=self):
+            result[f.name] = json.loads(f.value)
 
         return result
 
@@ -298,20 +295,24 @@ class Activity(models.Model):
             # with local URLs, which is weird and shouldn't happen.
             record_fields['remote_url'] = value['id']
 
-        for f in ['id', 'type']:
+        for f in ['id', 'type', 'actor']:
             if f in other_fields:
                 del other_fields[f]
 
-        record_fields['other_fields'] = json.dumps(
-                other_fields,
-                sort_keys=True,
-                )
-
         logger.debug('About to create Activity with fields: %s', record_fields)
 
         result = cls(**record_fields)
         result.save()
-        logger.debug('Activity created: %s', record_fields)
+        logger.debug('Activity created: %s', result)
+
+        for f, v in other_fields.items():
+            n = ActivityField(
+                    parent = result,
+                    name = f,
+                    value = json.dumps(v, sort_keys=True),
+                    )
+            n.save()
+            logger.debug('ActivityField created: %s', n)
 
         if run_side_effects:
             result.send_notifications()
@@ -323,4 +324,32 @@ class Activity(models.Model):
 
 ########################################
 
+class ActivityField(models.Model):
+
+    class Meta:
+        unique_together = ['parent', 'name']
+
+    parent = models.ForeignKey(
+            Activity,
+            on_delete=models.CASCADE,
+            )
+
+    # "type" and "actor" are fields in the Activity model itself;
+    # all ohers go here.
+    name = models.CharField(
+            max_length=255,
+            )
+
+    # Stored in JSON.
+    value = models.TextField(
+        )
+
+    def __str__(self):
+        return '%s.%s = %s' % (
+                self.parent.uuid,
+                self.name,
+                self.value)
+
+########################################
+
 Activity.register_all_activity_types()
diff --git a/django_kepi/migrations/0021_auto_20190516_1515.py b/django_kepi/migrations/0021_auto_20190516_1515.py
new file mode 100644
index 0000000..8b7d1e5
--- /dev/null
+++ b/django_kepi/migrations/0021_auto_20190516_1515.py
@@ -0,0 +1,35 @@
+# Generated by Django 2.1.5 on 2019-05-16 15:15
+
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('django_kepi', '0020_auto_20190516_1451'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='ActivityField',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('name', models.CharField(max_length=255)),
+                ('value', models.TextField()),
+            ],
+        ),
+        migrations.RemoveField(
+            model_name='activity',
+            name='other_fields',
+        ),
+        migrations.AddField(
+            model_name='activityfield',
+            name='parent',
+            field=models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, to='django_kepi.Activity'),
+        ),
+        migrations.AlterUniqueTogether(
+            name='activityfield',
+            unique_together={('parent', 'name')},
+        ),
+    ]