diff --git src/wp-admin/includes/class-wp-screen.php src/wp-admin/includes/class-wp-screen.php
index 2537319..7f17c75 100644
--- src/wp-admin/includes/class-wp-screen.php
+++ src/wp-admin/includes/class-wp-screen.php
@@ -530,7 +530,7 @@ final class WP_Screen {
 			}
 		}
 
-		sort( $priorities );
+		ksort( $priorities );
 
 		$sorted = array();
 		foreach ( $priorities as $list ) {
@@ -998,7 +998,7 @@ final class WP_Screen {
 		 * Filter whether to show the Screen Options submit button.
 		 *
 		 * @since 4.4.0
-		 * 
+		 *
 		 * @param bool      $show_button Whether to show Screen Options submit button.
 		 *                               Default false.
 		 * @param WP_Screen $this        Current WP_Screen instance.
diff --git tests/phpunit/tests/admin/includesScreen.php tests/phpunit/tests/admin/includesScreen.php
index 65603e3..484ab72 100644
--- tests/phpunit/tests/admin/includesScreen.php
+++ tests/phpunit/tests/admin/includesScreen.php
@@ -187,20 +187,28 @@ class Tests_Admin_includesScreen extends WP_UnitTestCase {
 	function test_help_tabs_priority() {
 		$tab_1      = rand_str();
 		$tab_1_args = array(
-			'id'       => $tab_1,
 			'title'    => 'Help!',
+			'id'       => $tab_1,
 			'content'  => 'Some content',
 			'callback' => false,
-			'priority' => 11,
+			'priority' => 10,
 		);
 
 		$tab_2      = rand_str();
 		$tab_2_args = array(
+			'title'    => 'Help!',
 			'id'       => $tab_2,
+			'content'  => 'Some content',
+			'callback' => false,
+			'priority' => 2,
+		);
+		$tab_3      = rand_str();
+		$tab_3_args = array(
 			'title'    => 'Help!',
+			'id'       => $tab_3,
 			'content'  => 'Some content',
 			'callback' => false,
-			'priority' => 9,
+			'priority' => 40,
 		);
 
 		$screen = get_current_screen();
@@ -213,28 +221,37 @@ class Tests_Admin_includesScreen extends WP_UnitTestCase {
 		$screen->add_help_tab( $tab_2_args );
 		$this->assertEquals( $screen->get_help_tab( $tab_2 ), $tab_2_args );
 
+		$screen->add_help_tab( $tab_3_args );
+		$this->assertEquals( $screen->get_help_tab( $tab_3 ), $tab_3_args );
+
 		$tabs = $screen->get_help_tabs();
-		$this->assertEquals( 2, count( $tabs ) );
+		$this->assertEquals( 3, count( $tabs ) );
 		$this->assertArrayHasKey( $tab_1, $tabs );
 		$this->assertArrayHasKey( $tab_2, $tabs );
+		$this->assertArrayHasKey( $tab_3, $tabs );
 
 		// Test priority order.
 
-		$this->assertEquals( $tabs, array(
+		$this->assertSame( array(
 			$tab_2 => $tab_2_args,
 			$tab_1 => $tab_1_args,
-		) );
+			$tab_3 => $tab_3_args,
+		), $tabs );
 
 		$screen->remove_help_tab( $tab_1 );
 		$this->assertNull( $screen->get_help_tab( $tab_1 ) );
-		$this->assertEquals( 1, count( $screen->get_help_tabs() ) );
+		$this->assertSame( 2, count( $screen->get_help_tabs() ) );
 
 		$screen->remove_help_tab( $tab_2 );
 		$this->assertNull( $screen->get_help_tab( $tab_2 ) );
-		$this->assertEquals( 0, count( $screen->get_help_tabs() ) );
+		$this->assertSame( 1, count( $screen->get_help_tabs() ) );
+
+		$screen->remove_help_tab( $tab_3 );
+		$this->assertNull( $screen->get_help_tab( $tab_3 ) );
+		$this->assertSame( 0, count( $screen->get_help_tabs() ) );
 
 		$screen->remove_help_tabs();
-		$this->assertEquals( $screen->get_help_tabs(), array() );
+		$this->assertEquals( array(), $screen->get_help_tabs() );
 	}
 
 	/**