diff --git a/Classes/Domain/Index/TcaIndexer/RelationResolver.php b/Classes/Domain/Index/TcaIndexer/RelationResolver.php
index ae47e30..763589b 100644
--- a/Classes/Domain/Index/TcaIndexer/RelationResolver.php
+++ b/Classes/Domain/Index/TcaIndexer/RelationResolver.php
@@ -82,7 +82,7 @@ class RelationResolver implements Singleton
     protected function isRelation(array &$config) : bool
     {
         return isset($config['foreign_table'])
-            || (isset($config['renderType']) && $config['renderType'] !== 'selectSingle')
+            || (isset($config['renderType']) && !in_array($config['renderType'], ['selectSingle', 'inputDateTime']))
             || (isset($config['internal_type']) && strtolower($config['internal_type']) === 'db')
             ;
     }
diff --git a/Tests/Unit/Domain/Index/TcaIndexer/RelationResolverTest.php b/Tests/Unit/Domain/Index/TcaIndexer/RelationResolverTest.php
new file mode 100644
index 0000000..c227c24
--- /dev/null
+++ b/Tests/Unit/Domain/Index/TcaIndexer/RelationResolverTest.php
@@ -0,0 +1,83 @@
+<?php
+namespace Codappix\SearchCore\Tests\Unit\Domain\Index\TcaIndexer;
+
+/*
+ * Copyright (C) 2018  Daniel Siepmann <coding@daniel-siepmann.de>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+use Codappix\SearchCore\Domain\Index\TcaIndexer\RelationResolver;
+use Codappix\SearchCore\Domain\Index\TcaIndexer\TcaTableServiceInterface;
+use Codappix\SearchCore\Tests\Unit\AbstractUnitTestCase;
+
+class RelationResolverTest extends AbstractUnitTestCase
+{
+    /**
+     * @var RelationResolver
+     */
+    protected $subject;
+
+    public function setUp()
+    {
+        parent::setUp();
+        $this->subject = new RelationResolver();
+    }
+
+    /**
+     * @test
+     */
+    public function renderTypeInputDateTimeIsHandled()
+    {
+        $originalRecord = [
+            'starttime' => 0,
+        ];
+        $record = $originalRecord;
+        $GLOBALS['TCA'] = [
+            'tt_content' => [
+                'columns' => [
+                    'starttime' => [
+                        'config' => [
+                            'default' => 0,
+                            'eval' => 'datetime',
+                            'renderType' => 'inputDateTime',
+                        ],
+                        'type' => 'input',
+                        'exclude' => 1,
+                        'l10n_display' => 'defaultAsReadonly',
+                        'l10n_mode' => 'exclude',
+                        'label' => 'LLL:EXT:lang/Resources/Private/Language/locallang_general.xlf:LGL.starttime',
+                    ],
+                ],
+            ],
+        ];
+        $tableServiceMock = $this->getMockBuilder(TcaTableServiceInterface::class)->getMock();
+        $tableServiceMock->expects($this->any())
+            ->method('getTableName')
+            ->willReturn('tt_content');
+        $tableServiceMock->expects($this->any())
+            ->method('getColumnConfig')
+            ->willReturn($GLOBALS['TCA']['tt_content']['columns']['starttime']['config']);
+
+        $this->subject->resolveRelationsForRecord($tableServiceMock, $record);
+
+        $this->assertSame(
+            $originalRecord,
+            $record,
+            'TCA column configured with renderType inputDateTime was not kept as unix timestamp.'
+        );
+    }
+}