diff --git a/src/wp-includes/theme.php b/src/wp-includes/theme.php
index 662df894b3..ecbedec482 100644
--- a/src/wp-includes/theme.php
+++ b/src/wp-includes/theme.php
@@ -413,8 +413,6 @@ function register_theme_directory( $directory ) {
 		$wp_theme_directories[] = $untrailed;
 	}
 
-	wp_clean_themes_cache();
-
 	return true;
 }
 
diff --git a/tests/phpunit/tests/theme/themeDir.php b/tests/phpunit/tests/theme/themeDir.php
index 4e915aeb40..2cab375b1a 100644
--- a/tests/phpunit/tests/theme/themeDir.php
+++ b/tests/phpunit/tests/theme/themeDir.php
@@ -293,24 +293,4 @@ class Tests_Theme_ThemeDir extends WP_UnitTestCase {
 		rmdir( WP_CONTENT_DIR . '/themes/foo' );
 		rmdir( WP_CONTENT_DIR . '/themes/foo-themes' );
 	}
-
-	/**
-	 * @ticket 43228
-	 */
-	function test_theme_dir_caches() {
-		@mkdir( WP_CONTENT_DIR . '/themes/foo' );
-		@mkdir( WP_CONTENT_DIR . '/themes/foo/bar' );
-
-		$old_roots = get_theme_roots();
-
-		register_theme_directory( WP_CONTENT_DIR . '/themes/foo' );
-
-		$new_roots = get_theme_roots();
-
-		rmdir( WP_CONTENT_DIR . '/themes/foo/bar' );
-		rmdir( WP_CONTENT_DIR . '/themes/foo' );
-
-		$this->assertNotEquals( $new_roots, $old_roots );
-		$this->assertArrayHasKey( 'foo', $new_roots );
-	}
 }