diff --git a/tests/phpunit/tests/comment/query.php b/tests/phpunit/tests/comment/query.php
index 7003f2ab0b..27a23870f8 100644
--- a/tests/phpunit/tests/comment/query.php
+++ b/tests/phpunit/tests/comment/query.php
@@ -1108,6 +1108,17 @@ class Tests_Comment_Query extends WP_UnitTestCase {
 		$this->assertContains( "ORDER BY $wpdb->comments.comment_date_gmt", $q->request );
 	}
 
+	public function test_orderby_space_separated() {
+		global $wpdb;
+
+		$q = new WP_Comment_Query();
+		$q->query( array(
+			'orderby' => 'comment_agent comment_approved',
+		) );
+
+		$this->assertContains( "ORDER BY $wpdb->comments.comment_agent DESC, $wpdb->comments.comment_approved DESC", $q->request );
+	}
+
 	public function test_orderby_comma_separated() {
 		global $wpdb;
 
diff --git a/tests/phpunit/tests/query.php b/tests/phpunit/tests/query.php
index c1aa6df309..f12dccc41d 100644
--- a/tests/phpunit/tests/query.php
+++ b/tests/phpunit/tests/query.php
@@ -122,4 +122,15 @@ class Tests_Query extends WP_UnitTestCase {
 	public function filter_parse_query_to_remove_tax( $q ) {
 		unset( $q->query_vars['wptests_tax'] );
 	}
+
+	public function test_orderby_space_separated() {
+		global $wpdb;
+
+		$q = new WP_Query( array(
+			'orderby' => 'title date',
+			'order' => 'DESC',
+		) );
+
+		$this->assertContains( "ORDER BY $wpdb->posts.post_title DESC, $wpdb->posts.post_date DESC", $q->request );
+	}
 }
diff --git a/tests/phpunit/tests/user/query.php b/tests/phpunit/tests/user/query.php
index 37b8d6759a..c2adee1e84 100644
--- a/tests/phpunit/tests/user/query.php
+++ b/tests/phpunit/tests/user/query.php
@@ -113,6 +113,27 @@ class Tests_User_Query extends WP_UnitTestCase {
 		}
 	}
 
+	/**
+	 * @dataProvider orderby_should_convert_non_prefixed_keys_data
+	 */
+	public function test_orderby_should_convert_non_prefixed_keys( $short_key, $full_key ) {
+		$q = new WP_User_Query( array(
+			'orderby' => $short_key,
+		) );
+
+		$this->assertContains( "ORDER BY $full_key", $q->query_orderby );
+	}
+
+	public function orderby_should_convert_non_prefixed_keys_data() {
+		return array(
+			array( 'nicename', 'user_nicename' ),
+			array( 'email', 'user_email' ),
+			array( 'url', 'user_url' ),
+			array( 'registered', 'user_registered' ),
+			array( 'name', 'display_name' ),
+		);
+	}
+
 	public function test_orderby_meta_value() {
 		$users = $this->factory->user->create_many( 3, array(
 			'role' => 'author'