diff --git a/src/data/migrations/20210120231512_fix_moderator_role_overrides_thread_id_nullability.js b/src/data/migrations/20210120231512_fix_moderator_role_overrides_thread_id_nullability.js
new file mode 100644
index 0000000..cbad0ba
--- /dev/null
+++ b/src/data/migrations/20210120231512_fix_moderator_role_overrides_thread_id_nullability.js
@@ -0,0 +1,41 @@
+exports.up = async function(knex) {
+  await knex.schema.renameTable("moderator_role_overrides", "old_moderator_role_overrides");
+
+  await knex.schema.createTable("moderator_role_overrides", table => {
+    table.increments("id");
+    table.string("moderator_id", 20).notNullable();
+    table.string("thread_id", 36).nullable().defaultTo(null);
+    table.string("role_id", 20).notNullable();
+
+    table.unique(["moderator_id", "thread_id"]);
+  });
+
+  const rows = await knex.table("old_moderator_role_overrides")
+    .select();
+
+  await knex.table("moderator_role_overrides").insert(rows);
+
+  await knex.schema.dropTable("old_moderator_role_overrides");
+};
+
+exports.down = async function(knex) {
+  await knex.schema.renameTable("moderator_role_overrides", "new_moderator_role_overrides");
+
+  await knex.schema.createTable("moderator_role_overrides", table => {
+    table.string("moderator_id", 20);
+    table.string("thread_id", 36).nullable().defaultTo(null);
+    table.string("role_id", 20);
+
+    table.primary(["moderator_id", "thread_id"]);
+  });
+
+  const rows = await knex.table("new_moderator_role_overrides")
+    .select();
+
+  await knex.table("moderator_role_overrides").insert(rows.map(r => {
+    delete r.id;
+    return r;
+  }));
+
+  await knex.schema.dropTable("new_moderator_role_overrides");
+};