diff --git a/wp-admin/custom-header.php b/wp-admin/custom-header.php
index 4aeb8053c3..6ca3567f42 100644
--- a/wp-admin/custom-header.php
+++ b/wp-admin/custom-header.php
@@ -279,12 +279,13 @@ class Custom_Image_Header {
 			$header_thumbnail = $header['thumbnail_url'];
 			$header_url = $header['url'];
 			$header_desc = empty( $header['description'] ) ? '' : $header['description'];
+			$header_alt_text = empty( $header['alt_text'] ) ? $header_desc : $header['alt_text'];
 			echo '<div class="default-header">';
 			echo '<label><input name="default-header" type="radio" value="' . esc_attr( $header_key ) . '" ' . checked( $header_url, get_theme_mod( 'header_image' ), false ) . ' />';
 			$width = '';
 			if ( !empty( $header['attachment_id'] ) )
 				$width = ' width="230"';
-			echo '<img src="' . set_url_scheme( $header_thumbnail ) . '" alt="' . esc_attr( $header_desc ) .'" title="' . esc_attr( $header_desc ) . '"' . $width . ' /></label>';
+			echo '<img src="' . set_url_scheme( $header_thumbnail ) . '" alt="' . esc_attr( $header_alt_text ) .'" title="' . esc_attr( $header_desc ) . '"' . $width . ' /></label>';
 			echo '</div>';
 		}
 		echo '<div class="clear"></div></div>';
diff --git a/wp-includes/theme.php b/wp-includes/theme.php
index 65c7d3001f..e142795709 100644
--- a/wp-includes/theme.php
+++ b/wp-includes/theme.php
@@ -1209,10 +1209,13 @@ function get_uploaded_header_images() {
 		$url = esc_url_raw( wp_get_attachment_url( $header->ID ) );
 		$header_data = wp_get_attachment_metadata( $header->ID );
 		$header_index = basename($url);
+
 		$header_images[$header_index] = array();
-		$header_images[$header_index]['attachment_id'] =  $header->ID;
+		$header_images[$header_index]['attachment_id'] = $header->ID;
 		$header_images[$header_index]['url'] =  $url;
-		$header_images[$header_index]['thumbnail_url'] =  $url;
+		$header_images[$header_index]['thumbnail_url'] = $url;
+		$header_images[$header_index]['alt_text'] = get_post_meta( $header->ID, '_wp_attachment_image_alt', true );
+
 		if ( isset( $header_data['width'] ) )
 			$header_images[$header_index]['width'] = $header_data['width'];
 		if ( isset( $header_data['height'] ) )
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 4a706837e9..49068a0087 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.3-alpha-32997';
+$wp_version = '4.3-alpha-32998';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.