diff --git src/wp-admin/css/customize-controls.css src/wp-admin/css/customize-controls.css
index f9ca1d7..e9ef0f2 100644
--- src/wp-admin/css/customize-controls.css
+++ src/wp-admin/css/customize-controls.css
@@ -465,6 +465,16 @@ body {
 	margin-bottom: 18px;
 }

+#customize-control-header_image .uploaded button, #customize-control-header_image .default button {
+	width: 100%;
+	padding: 0;
+	margin: 0;
+	background: none;
+	border: none;
+	color: inherit;
+	cursor: pointer;
+}
+
 /* Header control: current image container */

 #customize-control-header_image .current .container {
diff --git src/wp-admin/custom-header.php src/wp-admin/custom-header.php
index 4a2d44c..2a6a2f3 100644
--- src/wp-admin/custom-header.php
+++ src/wp-admin/custom-header.php
@@ -1272,9 +1272,12 @@ wp_nonce_field( 'custom-header-options', '_wpnonce-custom-header-options' ); ?>
 	public function get_uploaded_header_images() {
 		$header_images = get_uploaded_header_images();
 		$timestamp_key = '_wp_attachment_custom_header_last_used_' . get_stylesheet();
+		$alt_text_key = '_wp_attachment_image_alt';

 		foreach ( $header_images as &$header_image ) {
-			$header_image['timestamp'] = get_post_meta( $header_image['attachment_id'], $timestamp_key, true );
+			$header_meta = get_post_meta( $header_image['attachment_id'] );
+			$header_image['timestamp'] = isset( $header_meta[ $timestamp_key ] ) ? $header_meta[ $timestamp_key ] : '';
+			$header_image['alt_text'] = isset( $header_meta[ $alt_text_key ] ) ? $header_meta[ $alt_text_key ] : '';
 		}

 		return $header_images;
diff --git src/wp-includes/class-wp-customize-control.php src/wp-includes/class-wp-customize-control.php
index e55a759..0b732c6 100644
--- src/wp-includes/class-wp-customize-control.php
+++ src/wp-includes/class-wp-customize-control.php
@@ -774,27 +774,28 @@ final class WP_Customize_Header_Image_Control extends WP_Customize_Image_Control

 			<div class="placeholder random">
 				<div class="inner">
-					<span><span class="dashicons dashicons-randomize dice"></span>
+					<button type="button"><span class="dashicons dashicons-randomize dice"></span>
 					<# if ( data.type === 'uploaded' ) { #>
 						<?php _e( 'Randomize uploaded headers' ); ?>
 					<# } else if ( data.type === 'default' ) { #>
 						<?php _e( 'Randomize suggested headers' ); ?>
 					<# } #>
-					</span>
+					</button>
 				</div>
 			</div>

 			<# } else { #>

 			<# if (data.type === 'uploaded') { #>
-			<div class="dashicons dashicons-no close"></div>
+				<div class="dashicons dashicons-no close"></div>
 			<# } #>

-			<a href="#" class="choice thumbnail #>"
+			<button type="button" class="choice thumbnail"
 				data-customize-image-value="{{{data.header.url}}}"
 				data-customize-header-image-data="{{JSON.stringify(data.header)}}">
-				<img src="{{{data.header.thumbnail_url}}}">
-			</a>
+				<span class="screen-reader-text"><?php _e( 'Set image' ); ?></span>
+				<img src="{{{data.header.thumbnail_url}}}" alt="{{{data.header.alt_text || data.header.description}}}">
+			</button>

 			<# } #>
 		</script>
@@ -875,9 +876,9 @@ final class WP_Customize_Header_Image_Control extends WP_Customize_Image_Control
 			</div>
 			<div class="actions">
 				<?php /* translators: Hide as in hide header image via the Customizer */ ?>
-				<a href="#" <?php echo $visibility ?> class="button remove"><?php _ex( 'Hide', 'custom header' ); ?></a>
+				<button type="button"<?php echo $visibility ?> class="button remove"><?php _ex( 'Hide image', 'custom header' ); ?></button>
 				<?php /* translators: New as in add new header image via the Customizer */ ?>
-				<a href="#" class="button new"><?php _ex( 'Add new', 'header image' ); ?></a>
+				<button type="button" class="button new"><?php _ex( 'Add new image', 'header image' ); ?></button>
 				<div style="clear:both"></div>
 			</div>
 			<div class="choices">