diff --git a/wp-includes/version.php b/wp-includes/version.php
index e5900953f2..5023a9c225 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.9-beta4-42029';
+$wp_version = '4.9-beta4-42030';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.
diff --git a/wp-includes/widgets/class-wp-widget-media-image.php b/wp-includes/widgets/class-wp-widget-media-image.php
index 780ceacad5..4ebc42d66e 100644
--- a/wp-includes/widgets/class-wp-widget-media-image.php
+++ b/wp-includes/widgets/class-wp-widget-media-image.php
@@ -177,8 +177,10 @@ class WP_Widget_Media_Image extends WP_Widget_Media {
 			$attachment = get_post( $instance['attachment_id'] );
 		}
 		if ( $attachment ) {
-			$caption = $attachment->post_excerpt;
-			if ( $instance['caption'] ) {
+			$caption = '';
+			if ( ! isset( $instance['caption'] ) ) {
+				$caption = $attachment->post_excerpt;
+			} elseif ( trim( $instance['caption'] ) ) {
 				$caption = $instance['caption'];
 			}