diff --git a/wp-includes/media.php b/wp-includes/media.php
index d4a0df3..7644710 100644
--- a/wp-includes/media.php
+++ b/wp-includes/media.php
@@ -2420,6 +2420,8 @@ function get_post_gallery_images( $post_id = 0 ) {
  *
  * @param string $attached_size If an attached image is found, the size to display it.
  * @param WP_Post $post Optional. Used instead of global $post when passed.
+ *
+ * @return string HTML for the image. Blank string if no image is found.
  */
 function get_the_post_format_image( $attached_size = 'full', &$post = null ) {
 	if ( empty( $post ) )
@@ -2566,6 +2568,15 @@ function get_the_post_format_image( $attached_size = 'full', &$post = null ) {
 		$post->format_content[ $cache_key ] = sprintf( $link_fmt, $html );
 		return $post->format_content[ $cache_key ];
 	}
+
+	$featured_image = get_the_post_thumbnail( $post->ID, $attached_size );
+	if ( ! empty( $featured_image ) ) {
+		$image = sprintf( $link_fmt, $featured_image );
+		$post->format_content[ $cache_key ] = $image;
+		return $image;
+	}
+
+	return '';
 }
 
 /**