diff --git a/wp-includes/class-wp-user.php b/wp-includes/class-wp-user.php
index 971021a759..b7887c4dc2 100644
--- a/wp-includes/class-wp-user.php
+++ b/wp-includes/class-wp-user.php
@@ -165,18 +165,24 @@ class WP_User {
 	 * Return only the main user fields
 	 *
 	 * @since 3.3.0
+	 * @since 4.4.0 Added 'ID' as an alias of 'id' for the `$field` parameter.
 	 *
 	 * @static
 	 *
 	 * @global wpdb $wpdb
 	 *
-	 * @param string $field The field to query against: 'id', 'slug', 'email' or 'login'
+	 * @param string $field The field to query against: 'id', 'ID', 'slug', 'email' or 'login'.
 	 * @param string|int $value The field value
 	 * @return object|false Raw user object
 	 */
 	public static function get_data_by( $field, $value ) {
 		global $wpdb;
 
+		// 'ID' is an alias of 'id'.
+		if ( 'ID' === $field ) {
+			$field = 'id';
+		}
+
 		if ( 'id' == $field ) {
 			// Make sure the value is numeric to avoid casting objects, for example,
 			// to int 1.
diff --git a/wp-includes/pluggable.php b/wp-includes/pluggable.php
index b53a233ea8..3317284381 100644
--- a/wp-includes/pluggable.php
+++ b/wp-includes/pluggable.php
@@ -145,8 +145,9 @@ if ( !function_exists('get_user_by') ) :
  * Retrieve user info by a given field
  *
  * @since 2.8.0
+ * @since 4.4.0 Added 'ID' as an alias of 'id' for the `$field` parameter.
  *
- * @param string     $field The field to retrieve the user with. id | slug | email | login
+ * @param string     $field The field to retrieve the user with. id | ID | slug | email | login.
  * @param int|string $value A value for $field. A user ID, slug, email address, or login name.
  * @return WP_User|false WP_User object on success, false on failure.
  */
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 29185d6527..36068e0392 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.4-alpha-34124';
+$wp_version = '4.4-alpha-34125';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.