diff --git a/src/wp-includes/class-wp-user-query.php b/src/wp-includes/class-wp-user-query.php
index 8a6a3cf8a4..a6ea048e05 100644
--- a/src/wp-includes/class-wp-user-query.php
+++ b/src/wp-includes/class-wp-user-query.php
@@ -419,7 +419,7 @@ class WP_User_Query {
 		$this->query_orderby = 'ORDER BY ' . implode( ', ', $orderby_array );
 
 		// limit
-		if ( isset( $qv['number'] ) && $qv['number'] ) {
+		if ( isset( $qv['number'] ) && $qv['number'] > 0 ) {
 			if ( $qv['offset'] ) {
 				$this->query_limit = $wpdb->prepare("LIMIT %d, %d", $qv['offset'], $qv['number']);
 			} else {
diff --git a/tests/phpunit/tests/user/query.php b/tests/phpunit/tests/user/query.php
index 98f63c18c6..f375a2294a 100644
--- a/tests/phpunit/tests/user/query.php
+++ b/tests/phpunit/tests/user/query.php
@@ -434,6 +434,26 @@ class Tests_User_Query extends WP_UnitTestCase {
 		$this->assertContains( "ORDER BY user_login DESC, user_email ASC", $q->query_orderby );
 	}
 
+	/**
+	 * @ticket 28631
+	 */
+	function test_number() {
+		$user_ids = $this->factory->user->create_many( 10 );
+
+		$users = new WP_User_Query( array( 'blog_id' => get_current_blog_id() ) );
+		$users = $users->get_results();
+
+		$this->assertEquals( 12, count( $users ) );
+
+		$users = new WP_User_Query( array( 'blog_id' => get_current_blog_id(), 'number' => 10 ) );
+		$users = $users->get_results();
+		$this->assertEquals( 10, count( $users ) );
+
+		$users = new WP_User_Query( array( 'blog_id' => get_current_blog_id(), 'number' => -1 ) );
+		$users = $users->get_results();
+		$this->assertEquals( 12, count( $users ) );
+	}
+
 	/**
 	 * @ticket 21119
 	 */
@@ -469,6 +489,10 @@ class Tests_User_Query extends WP_UnitTestCase {
 
 		$query->prepare_query();
 		$this->assertEquals( $_query_vars, $query->query_vars );
+
+		$query->prepare_query( array( 'number' => -1 ) );
+		$this->assertNotEquals( 'LIMIT -1', $query->query_limit );
+		$this->assertEmpty( $query->query_limit );
 	}
 
 	public function test_meta_vars_should_be_converted_to_meta_query() {