diff --git a/wp-includes/user.php b/wp-includes/user.php
index 1c8a5b36d4..fca15065f0 100644
--- a/wp-includes/user.php
+++ b/wp-includes/user.php
@@ -1945,7 +1945,7 @@ function wp_insert_user( $userdata ) {
 	 * check if current email and new email are the same, or not, and check `email_exists`
 	 * accordingly.
 	 */
-	if ( ( ! $update || ( ! empty( $old_user_data ) && $user_email !== $old_user_data->user_email ) )
+	if ( ( ! $update || ( ! empty( $old_user_data ) && 0 !== strcasecmp( $user_email, $old_user_data->user_email ) ) )
 		&& ! defined( 'WP_IMPORTING' )
 		&& email_exists( $user_email )
 	) {
diff --git a/wp-includes/version.php b/wp-includes/version.php
index aa6a25fb0c..a7f17a7a9f 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.3-beta1-33114';
+$wp_version = '4.3-beta1-33115';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.