diff --git a/tests/RUNNING_TESTS.txt b/tests/RUNNING_TESTS.txt
index ee2657c85f..cede81d59d 100644
--- a/tests/RUNNING_TESTS.txt
+++ b/tests/RUNNING_TESTS.txt
@@ -19,6 +19,7 @@ the following PHP extensions must be installed and enabled to run unit tests:
 
 - ctype (also a PHPUnit dependency)
 - dom (PHPUnit dependency)
+- json (also a phpBB dependency)
 
 Some of the functionality in phpBB and/or the test suite uses additional
 PHP extensions. If these extensions are not loaded, respective tests
@@ -29,8 +30,10 @@ will be skipped:
 - interbase, pdo_firebird (Firebird database driver)
 - mysql, pdo_mysql (MySQL database driver)
 - mysqli, pdo_mysql (MySQLi database driver)
+- pcntl (flock class)
 - pdo (any database tests)
 - pgsql, pdo_pgsql (PostgreSQL database driver)
+- redis (https://github.com/nicolasff/phpredis, Redis cache driver)
 - simplexml (any database tests)
 - sqlite, pdo_sqlite (SQLite database driver, requires SQLite 2.x support
   in pdo_sqlite)