diff --git a/src/bundle/Core/Resources/config/storage/legacy/schema.yaml b/src/bundle/Core/Resources/config/storage/legacy/schema.yaml
index 68353ee052..72615c3a5d 100644
--- a/src/bundle/Core/Resources/config/storage/legacy/schema.yaml
+++ b/src/bundle/Core/Resources/config/storage/legacy/schema.yaml
@@ -315,13 +315,14 @@ tables:
     ibexa_content_version:
         indexes:
             ibexa_content_version_status: { fields: [status] }
-            ibexa_content_version_idx_ver: { fields: [contentobject_id, version] }
             ibexa_content_version_idx_status: { fields: [contentobject_id, status] }
             ibexa_content_version_creator_id: { fields: [creator_id] }
+        uniqueConstraints:
+            ibexa_content_version_coid_version_unique: { fields: [contentobject_id, version] }
         id:
             id: { type: integer, nullable: false, options: { autoincrement: true } }
         fields:
-            contentobject_id: { type: integer, nullable: true }
+            contentobject_id: { type: integer, nullable: false }
             created: { type: integer, nullable: false, options: { default: '0' } }
             creator_id: { type: integer, nullable: false, options: { default: '0' } }
             initial_language_id: { type: bigint, nullable: false, options: { default: '0' } }
diff --git a/tests/integration/Core/Persistence/Legacy/Content/Gateway/DoctrineDatabaseTest.php b/tests/integration/Core/Persistence/Legacy/Content/Gateway/DoctrineDatabaseTest.php
new file mode 100644
index 0000000000..01628fdd26
--- /dev/null
+++ b/tests/integration/Core/Persistence/Legacy/Content/Gateway/DoctrineDatabaseTest.php
@@ -0,0 +1,75 @@
+<?php
+
+/**
+ * @copyright Copyright (C) Ibexa AS. All rights reserved.
+ * @license For full copyright and license information view LICENSE file distributed with this source code.
+ */
+declare(strict_types=1);
+
+namespace Ibexa\Tests\Integration\Core\Persistence\Legacy\Content\Gateway;
+
+use Doctrine\DBAL\Exception\UniqueConstraintViolationException;
+use Ibexa\Contracts\Core\Persistence\Content\ContentInfo;
+use Ibexa\Contracts\Core\Persistence\Content\VersionInfo;
+use Ibexa\Contracts\Core\Test\IbexaKernelTestCase;
+use Ibexa\Core\Persistence\Legacy\Content\Gateway\DoctrineDatabase;
+
+/**
+ * @internal
+ *
+ * @covers \Ibexa\Core\Persistence\Legacy\Content\Gateway\DoctrineDatabase
+ */
+final class DoctrineDatabaseTest extends IbexaKernelTestCase
+{
+    private const int CONTENT_ID = 2342;
+
+    private const int VERSION_NO = 1;
+
+    private DoctrineDatabase $gateway;
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+
+        self::loadSchema();
+        self::loadFixtures();
+
+        self::setAdministratorUser();
+
+        $gateway = self::getContainer()->get(DoctrineDatabase::class . '.inner');
+        self::assertInstanceOf(DoctrineDatabase::class, $gateway);
+
+        $this->gateway = $gateway;
+    }
+
+    public function testInsertVersionThrowsOnDuplicateContentIdAndVersionNo(): void
+    {
+        $versionInfo = $this->getVersionInfoFixture();
+
+        self::assertGreaterThan(0, $this->gateway->insertVersion($versionInfo, []));
+
+        $this->expectException(UniqueConstraintViolationException::class);
+        $this->gateway->insertVersion($versionInfo, []);
+    }
+
+    private function getVersionInfoFixture(): VersionInfo
+    {
+        $versionInfo = new VersionInfo();
+
+        $versionInfo->id = null;
+        $versionInfo->versionNo = self::VERSION_NO;
+        $versionInfo->creatorId = 14;
+        $versionInfo->status = VersionInfo::STATUS_DRAFT;
+        $versionInfo->creationDate = 1312278322;
+        $versionInfo->modificationDate = 1312278323;
+        $versionInfo->initialLanguageCode = 'eng-GB';
+        $versionInfo->contentInfo = new ContentInfo(
+            [
+                'id' => self::CONTENT_ID,
+                'alwaysAvailable' => true,
+            ]
+        );
+
+        return $versionInfo;
+    }
+}