diff --git a/src/Element/HttpQueryString.php b/src/Element/HttpQueryString.php
index 75cf05b..cdec590 100644
--- a/src/Element/HttpQueryString.php
+++ b/src/Element/HttpQueryString.php
@@ -25,7 +25,7 @@ class HttpQueryString implements \ArrayAccess {
    * @param array $initial
    *   The initial values of the query string.
    */
-  public function __construct($initial) {
+  public function __construct(array $initial) {
     $this->query = $initial;
   }
 
@@ -36,7 +36,7 @@ class HttpQueryString implements \ArrayAccess {
    *   A http query string.
    */
   function __toString() {
-    return http_build_query($this->query);
+    return (count($this->query) > 0 ? '?' : '') . http_build_query($this->query);
   }
 
   /**
diff --git a/src/Tests/Kernel/VideoEmbedIFrameTest.php b/src/Tests/Kernel/VideoEmbedIFrameTest.php
new file mode 100644
index 0000000..8c8a9c1
--- /dev/null
+++ b/src/Tests/Kernel/VideoEmbedIFrameTest.php
@@ -0,0 +1,97 @@
+<?php
+
+/**
+ * @file
+ *
+ */
+
+namespace Drupal\video_embed_field\Tests\Kernel;
+
+use Drupal\video_embed_field\Tests\KernelTestBase;
+
+class VideoEmbedIFrameTest extends KernelTestBase {
+
+  /**
+   * @return array
+   */
+  public function videoEmbedIFrameTestCases() {
+    return [
+      'Default' => [
+        [
+          '#type' => 'video_embed_iframe',
+        ],
+        '<iframe></iframe>',
+      ],
+      'URL' => [
+        [
+          '#type' => 'video_embed_iframe',
+          '#url' => 'https://www.youtube.com/embed/fdbFVWupSsw',
+        ],
+        '<iframe src="https://www.youtube.com/embed/fdbFVWupSsw"></iframe>',
+      ],
+      'URL, query' => [
+        [
+          '#type' => 'video_embed_iframe',
+          '#url' => 'https://www.youtube.com/embed/fdbFVWupSsw',
+          '#query' => ['autoplay' => '1'],
+        ],
+        '<iframe src="https://www.youtube.com/embed/fdbFVWupSsw?autoplay=1"></iframe>',
+      ],
+      'URL, query, attributes' => [
+        [
+          '#type' => 'video_embed_iframe',
+          '#url' => 'https://www.youtube.com/embed/fdbFVWupSsw',
+          '#query' => ['autoplay' => '1'],
+          '#attributes' => [
+            'width' => '100',
+          ],
+        ],
+        '<iframe width="100" src="https://www.youtube.com/embed/fdbFVWupSsw?autoplay=1"></iframe>',
+      ],
+      'Query' => [
+        [
+          '#type' => 'video_embed_iframe',
+          '#query' => ['autoplay' => '1'],
+        ],
+        '<iframe></iframe>',
+      ],
+      'Query, attributes' => [
+        [
+          '#type' => 'video_embed_iframe',
+          '#query' => ['autoplay' => '1'],
+          '#attributes' => [
+            'width' => '100',
+          ],
+        ],
+        '<iframe width="100"></iframe>',
+      ],
+      'Attributes' => [
+        [
+          '#type' => 'video_embed_iframe',
+          '#attributes' => [
+            'width' => '100',
+          ],
+        ],
+        '<iframe width="100"></iframe>',
+      ],
+    ];
+  }
+
+  /**
+   * Test the video embed iframe renders correctly.
+   *
+   * @dataProvider videoEmbedIFrameTestCases
+   */
+  public function testVideoEmbedIFrame($renderable, $markup) {
+    $this->assertEquals($markup, trim($this->container->get('renderer')->renderRoot($renderable)));
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    parent::setUp();
+
+  }
+
+}
diff --git a/templates/video-embed-iframe.html.twig b/templates/video-embed-iframe.html.twig
index 8f9b3d9..5792125 100644
--- a/templates/video-embed-iframe.html.twig
+++ b/templates/video-embed-iframe.html.twig
@@ -1 +1 @@
-<iframe {{ attributes }} src="{{ url }}?{{ query }}"></iframe>
+<iframe{{ attributes }}{% if url is not empty %} src="{{ url }}{{ query }}"{% endif %}></iframe>
diff --git a/tests/src/Unit/HttpQueryStringTest.php b/tests/src/Unit/HttpQueryStringTest.php
new file mode 100644
index 0000000..15bd258
--- /dev/null
+++ b/tests/src/Unit/HttpQueryStringTest.php
@@ -0,0 +1,51 @@
+<?php
+
+/**
+ * @file
+ * Contains Drupal\Tests\video_embed_field\Unit\HttpQueryStringTest.
+ */
+
+namespace Drupal\Tests\video_embed_field\Unit;
+
+use Drupal\Tests\UnitTestCase;
+use Drupal\video_embed_field\Element\HttpQueryString;
+
+/**
+ * Test the HTTP query string object.
+ *
+ * @group video_embed_field
+ */
+class HttpQueryStringTest extends UnitTestCase {
+
+  /**
+   * Data provider for testHttpQueryObject.
+   */
+  public function httpQueryObjectTestCases() {
+    return [
+      'Normal query string' => [
+        [
+          'cat' => 'house',
+          'fish' => 'bowl',
+        ],
+        '?cat=house&fish=bowl',
+      ],
+      'Boolean value' => [
+        [
+          'autoplay' => TRUE,
+        ],
+        '?autoplay=1',
+      ],
+      'Empty initial input' => [
+        [],
+        '',
+      ],
+    ];
+  }
+
+  /**
+   * @dataProvider httpQueryObjectTestCases
+   */
+  public function testHttpQueryObject($initial, $expected) {
+    $this->assertEquals((string) new HttpQueryString($initial), $expected);
+  }
+}