diff --git a/assets/css/amp-default.css b/assets/css/amp-default.css
index 1779a20aff8..77e7e909268 100644
--- a/assets/css/amp-default.css
+++ b/assets/css/amp-default.css
@@ -14,7 +14,7 @@ amp-fit-text h6 {
 	font-size: inherit;
 }
 
-#amp-image-lightbox-1 img {
+#amp-image-lightbox .i-amphtml-image-lightbox-viewer-image {
 	object-fit: contain;
 }
 
diff --git a/includes/sanitizers/class-amp-base-sanitizer.php b/includes/sanitizers/class-amp-base-sanitizer.php
index d339d2382a2..4e186e4ce8c 100644
--- a/includes/sanitizers/class-amp-base-sanitizer.php
+++ b/includes/sanitizers/class-amp-base-sanitizer.php
@@ -26,7 +26,7 @@ abstract class AMP_Base_Sanitizer {
 	 *
 	 * @const string
 	 */
-	const AMP_IMAGE_LIGHTBOX_ID = 'amp-image-lightbox-1';
+	const AMP_IMAGE_LIGHTBOX_ID = 'amp-image-lightbox';
 
 	/**
 	 * Placeholder for default args, to be set in child classes.
diff --git a/tests/test-class-amp-gallery-block-sanitizer.php b/tests/test-class-amp-gallery-block-sanitizer.php
index b5c461113ed..611ef71d41b 100644
--- a/tests/test-class-amp-gallery-block-sanitizer.php
+++ b/tests/test-class-amp-gallery-block-sanitizer.php
@@ -39,12 +39,12 @@ public function get_data() {
 
 			'data_amp_with_lightbox'              => array(
 				'<ul data-amp-lightbox="true"><li class="blocks-gallery-item"><figure><a href="http://example.com"><amp-img src="http://example.com/img.png" width="600" height="400"></amp-img></a></figure></li></ul>',
-				'<ul data-amp-lightbox="true"><li class="blocks-gallery-item"><figure><a href="http://example.com"><amp-img src="http://example.com/img.png" width="600" height="400" data-amp-lightbox="" on="tap:amp-image-lightbox-1" role="button"></amp-img></a></figure></li></ul><amp-image-lightbox id="amp-image-lightbox-1" layout="nodisplay" data-close-button-aria-label="Close"></amp-image-lightbox>',
+				'<ul data-amp-lightbox="true"><li class="blocks-gallery-item"><figure><a href="http://example.com"><amp-img src="http://example.com/img.png" width="600" height="400" data-amp-lightbox="" on="tap:amp-image-lightbox" role="button"></amp-img></a></figure></li></ul><amp-image-lightbox id="amp-image-lightbox" layout="nodisplay" data-close-button-aria-label="Close"></amp-image-lightbox>',
 			),
 
 			'data_amp_with_lightbox_and_carousel' => array(
 				'<ul data-amp-lightbox="true" data-amp-carousel="true"><li class="blocks-gallery-item"><figure><a href="http://example.com"><amp-img src="http://example.com/img.png" width="600" height="400"></amp-img></a></figure></li></ul>',
-				'<amp-carousel height="400" type="slides" layout="fixed-height"><amp-img src="http://example.com/img.png" width="600" height="400" data-amp-lightbox="" on="tap:amp-image-lightbox-1" role="button"></amp-img></amp-carousel><amp-image-lightbox id="amp-image-lightbox-1" layout="nodisplay" data-close-button-aria-label="Close"></amp-image-lightbox>',
+				'<amp-carousel height="400" type="slides" layout="fixed-height"><amp-img src="http://example.com/img.png" width="600" height="400" data-amp-lightbox="" on="tap:amp-image-lightbox" role="button"></amp-img></amp-carousel><amp-image-lightbox id="amp-image-lightbox" layout="nodisplay" data-close-button-aria-label="Close"></amp-image-lightbox>',
 			),
 		);
 	}