diff --git a/includes/amp-helper-functions.php b/includes/amp-helper-functions.php
index 5d8424eb9c2..9ce4801e953 100644
--- a/includes/amp-helper-functions.php
+++ b/includes/amp-helper-functions.php
@@ -1652,7 +1652,7 @@ function amp_get_content_sanitizers( $post = null ) {
 		// Mark the script output by wp_post_preview_js() as being in dev mode.
 		if ( is_preview() && get_queried_object() instanceof WP_Post ) {
 			$dev_mode_xpaths[] = sprintf(
-				'//script[ not( @src ) and contains( text(), "document.location.search" ) and contains( text(), "preview=true" ) and contains( text(), "unload" ) and contains( text(), "window.name" ) and contains( text(), "wp-preview-%d" ) ]',
+				'//script[ not( @src ) and contains( text(), "document.location.search" ) and contains( text(), "preview=true" ) and ( contains( text(), "pagehide" ) or contains( text(), "unload" ) ) and contains( text(), "window.name" ) and contains( text(), "wp-preview-%d" ) ]',
 				get_queried_object_id()
 			);
 		}
diff --git a/tests/php/test-amp-helper-functions.php b/tests/php/test-amp-helper-functions.php
index f19f55b8292..096c4b873a1 100644
--- a/tests/php/test-amp-helper-functions.php
+++ b/tests/php/test-amp-helper-functions.php
@@ -1938,7 +1938,7 @@ static function () {
 				'//*[ @id = "wpadminbar" ]',
 				'//*[ @id = "wpadminbar" ]//*',
 				'//style[ @id = "admin-bar-inline-css" ]',
-				'//script[ not( @src ) and contains( text(), "document.location.search" ) and contains( text(), "preview=true" ) and contains( text(), "unload" ) and contains( text(), "window.name" ) and contains( text(), "wp-preview-' . $post . '" ) ]',
+				'//script[ not( @src ) and contains( text(), "document.location.search" ) and contains( text(), "preview=true" ) and ( contains( text(), "pagehide" ) or contains( text(), "unload" ) ) and contains( text(), "window.name" ) and contains( text(), "wp-preview-' . $post . '" ) ]',
 				'//link[@rel="manifest" and contains(@href, "web-app-manifest")]',
 			],
 			$sanitizers[ AMP_Dev_Mode_Sanitizer::class ]['element_xpaths']