diff --git a/wp-includes/kses.php b/wp-includes/kses.php
index 93fc9dd00b..265fb748ac 100644
--- a/wp-includes/kses.php
+++ b/wp-includes/kses.php
@@ -1047,7 +1047,8 @@ function wp_kses_attr( $element, $attr, $allowed_html, $allowed_protocols ) {
 	}
 
 	// Are any attributes allowed at all for this element?
-	if ( ! isset( $allowed_html[ strtolower( $element ) ] ) || true === $allowed_html[ strtolower( $element ) ] || count( $allowed_html[ strtolower( $element ) ] ) == 0 ) {
+	$element_low = strtolower( $element );
+	if ( empty( $allowed_html[ $element_low ] ) || true === $allowed_html[ $element_low ] ) {
 		return "<$element$xhtml_slash>";
 	}
 
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 2a7ce8cdbe..5900ba5af4 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.0-alpha-42858';
+$wp_version = '5.0-alpha-42860';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.