diff --git a/phpBB/includes/cron/cron_manager.php b/phpBB/includes/cron/cron_manager.php
index 84b9c9783c..a99f1369de 100644
--- a/phpBB/includes/cron/cron_manager.php
+++ b/phpBB/includes/cron/cron_manager.php
@@ -16,7 +16,10 @@ if (!defined('IN_PHPBB'))
 	exit;
 }
 
-include_once($phpbb_root_path . 'includes/cron/cron_task_wrapper.' . $phpEx);
+if (!class_exists('cron_task_wrapper'))
+{
+	include($phpbb_root_path . 'includes/cron/cron_task_wrapper.' . $phpEx);
+}
 
 /**
 * Cron manager class.
@@ -100,8 +103,11 @@ class cron_manager
 			list($mod, $filename) = $task_file;
 			if ($this->is_valid_name($mod) && $this->is_valid_name($filename))
 			{
-				include_once($phpbb_root_path . "includes/cron/$mod/$filename.$phpEx");
 				$class = "cron_task_${mod}_${filename}";
+				if (!class_exists($class))
+				{
+					include($phpbb_root_path . "includes/cron/$mod/$filename.$phpEx");
+				}
 				$object = new $class;
 				$wrapper = new cron_task_wrapper($object);
 				$this->tasks[] = $wrapper;
diff --git a/phpBB/includes/cron/cron_task_base.php b/phpBB/includes/cron/cron_task_base.php
index bdd96ec8f5..a75e27ac13 100644
--- a/phpBB/includes/cron/cron_task_base.php
+++ b/phpBB/includes/cron/cron_task_base.php
@@ -16,7 +16,10 @@ if (!defined('IN_PHPBB'))
 	exit;
 }
 
-include_once($phpbb_root_path . 'includes/cron/cron_task.' . $phpEx);
+if (!class_exists('cron_task'))
+{
+	include_once($phpbb_root_path . 'includes/cron/cron_task.' . $phpEx);
+}
 
 /**
 * Cron task base class. Provides sensible defaults for cron tasks
diff --git a/phpBB/includes/cron/cron_task_wrapper.php b/phpBB/includes/cron/cron_task_wrapper.php
index 0e63000846..00b330464e 100644
--- a/phpBB/includes/cron/cron_task_wrapper.php
+++ b/phpBB/includes/cron/cron_task_wrapper.php
@@ -16,6 +16,12 @@ if (!defined('IN_PHPBB'))
 	exit;
 }
 
+// We use parametrized_cron_task in is_parametrized
+if (!interface_exists('cron_task'))
+{
+	include($phpbb_root_path . 'includes/cron/cron_task.' . $phpEx);
+}
+
 /**
 * Cron task wrapper class.
 * Enhances cron tasks with convenience methods that work identically for all tasks.
diff --git a/phpBB/includes/cron/tasks/core/prune_all_forums.php b/phpBB/includes/cron/tasks/core/prune_all_forums.php
index 23d8a05d92..ebd09cbade 100644
--- a/phpBB/includes/cron/tasks/core/prune_all_forums.php
+++ b/phpBB/includes/cron/tasks/core/prune_all_forums.php
@@ -16,7 +16,10 @@ if (!defined('IN_PHPBB'))
 	exit;
 }
 
-include_once($phpbb_root_path . 'includes/cron/cron_task_base.' . $phpEx);
+if (!class_exists('cron_task_base'))
+{
+	include($phpbb_root_path . 'includes/cron/cron_task_base.' . $phpEx);
+}
 
 /**
 * Prune all forums cron task.
diff --git a/phpBB/includes/cron/tasks/core/prune_forum.php b/phpBB/includes/cron/tasks/core/prune_forum.php
index 93023ce38d..bfc8beb2de 100644
--- a/phpBB/includes/cron/tasks/core/prune_forum.php
+++ b/phpBB/includes/cron/tasks/core/prune_forum.php
@@ -16,7 +16,10 @@ if (!defined('IN_PHPBB'))
 	exit;
 }
 
-include_once($phpbb_root_path . 'includes/cron/cron_task_base.' . $phpEx);
+if (!class_exists('cron_task_base'))
+{
+	include($phpbb_root_path . 'includes/cron/cron_task_base.' . $phpEx);
+}
 
 /**
 * Prune one forum cron task.
@@ -60,7 +63,10 @@ class cron_task_core_prune_forum extends cron_task_base implements parametrized_
 	public function run()
 	{
 		global $phpbb_root_path, $phpEx;
-		include_once($phpbb_root_path . 'includes/functions_admin.' . $phpEx);
+		if (!function_exists('auto_prune'))
+		{
+			include($phpbb_root_path . 'includes/functions_admin.' . $phpEx);
+		}
 
 		if ($this->forum_data['prune_days'])
 		{
diff --git a/phpBB/includes/cron/tasks/core/queue.php b/phpBB/includes/cron/tasks/core/queue.php
index 37a9d1aceb..5b6b69c269 100644
--- a/phpBB/includes/cron/tasks/core/queue.php
+++ b/phpBB/includes/cron/tasks/core/queue.php
@@ -16,7 +16,10 @@ if (!defined('IN_PHPBB'))
 	exit;
 }
 
-include_once($phpbb_root_path . 'includes/cron/cron_task_base.' . $phpEx);
+if (!class_exists('cron_task_base'))
+{
+	include($phpbb_root_path . 'includes/cron/cron_task_base.' . $phpEx);
+}
 
 /**
 * Queue cron task. Sends email and jabber messages queued by other scripts.
@@ -31,7 +34,10 @@ class cron_task_core_queue extends cron_task_base
 	public function run()
 	{
 		global $phpbb_root_path, $phpEx;
-		include_once($phpbb_root_path . 'includes/functions_messenger.' . $phpEx);
+		if (!class_exists('queue'))
+		{
+			include($phpbb_root_path . 'includes/functions_messenger.' . $phpEx);
+		}
 		$queue = new queue();
 		$queue->process();
 	}
diff --git a/phpBB/includes/cron/tasks/core/tidy_cache.php b/phpBB/includes/cron/tasks/core/tidy_cache.php
index 5be27c3a42..72843ba680 100644
--- a/phpBB/includes/cron/tasks/core/tidy_cache.php
+++ b/phpBB/includes/cron/tasks/core/tidy_cache.php
@@ -16,7 +16,10 @@ if (!defined('IN_PHPBB'))
 	exit;
 }
 
-include_once($phpbb_root_path . 'includes/cron/cron_task_base.' . $phpEx);
+if (!class_exists('cron_task_base'))
+{
+	include($phpbb_root_path . 'includes/cron/cron_task_base.' . $phpEx);
+}
 
 /**
 * Tidy cache cron task.
diff --git a/phpBB/includes/cron/tasks/core/tidy_database.php b/phpBB/includes/cron/tasks/core/tidy_database.php
index 715ab2250e..f2de216c3a 100644
--- a/phpBB/includes/cron/tasks/core/tidy_database.php
+++ b/phpBB/includes/cron/tasks/core/tidy_database.php
@@ -16,7 +16,10 @@ if (!defined('IN_PHPBB'))
 	exit;
 }
 
-include_once($phpbb_root_path . 'includes/cron/cron_task_base.' . $phpEx);
+if (!class_exists('cron_task_base'))
+{
+	include($phpbb_root_path . 'includes/cron/cron_task_base.' . $phpEx);
+}
 
 /**
 * Tidy database cron task.
@@ -30,7 +33,10 @@ class cron_task_core_tidy_database extends cron_task_base
 	*/
 	public function run()
 	{
-		include_once($phpbb_root_path . 'includes/functions_admin.' . $phpEx);
+		if (!function_exists('tidy_database'))
+		{
+			include($phpbb_root_path . 'includes/functions_admin.' . $phpEx);
+		}
 		tidy_database();
 	}
 
diff --git a/phpBB/includes/cron/tasks/core/tidy_search.php b/phpBB/includes/cron/tasks/core/tidy_search.php
index 42120cdf17..42a46142b1 100644
--- a/phpBB/includes/cron/tasks/core/tidy_search.php
+++ b/phpBB/includes/cron/tasks/core/tidy_search.php
@@ -16,7 +16,10 @@ if (!defined('IN_PHPBB'))
 	exit;
 }
 
-include_once($phpbb_root_path . 'includes/cron/cron_task_base.' . $phpEx);
+if (!class_exists('cron_task_base'))
+{
+	include($phpbb_root_path . 'includes/cron/cron_task_base.' . $phpEx);
+}
 
 /**
 * Tidy search cron task.
@@ -37,7 +40,10 @@ class cron_task_core_tidy_sessions extends cron_task_base
 		// Select the search method
 		$search_type = basename($config['search_type']);
 
-		include_once("{$phpbb_root_path}includes/search/$search_type.$phpEx");
+		if (!class_exists($search_type))
+		{
+			include("{$phpbb_root_path}includes/search/$search_type.$phpEx");
+		}
 
 		// We do some additional checks in the module to ensure it can actually be utilised
 		$error = false;
diff --git a/phpBB/includes/cron/tasks/core/tidy_sessions.php b/phpBB/includes/cron/tasks/core/tidy_sessions.php
index cf02058c62..ecf0be3978 100644
--- a/phpBB/includes/cron/tasks/core/tidy_sessions.php
+++ b/phpBB/includes/cron/tasks/core/tidy_sessions.php
@@ -16,7 +16,10 @@ if (!defined('IN_PHPBB'))
 	exit;
 }
 
-include_once($phpbb_root_path . 'includes/cron/cron_task_base.' . $phpEx);
+if (!class_exists('cron_task_base'))
+{
+	include($phpbb_root_path . 'includes/cron/cron_task_base.' . $phpEx);
+}
 
 /**
 * Tidy sessions cron task.
diff --git a/phpBB/includes/cron/tasks/core/tidy_warnings.php b/phpBB/includes/cron/tasks/core/tidy_warnings.php
index 20a4bcbc60..4d70f3dc3d 100644
--- a/phpBB/includes/cron/tasks/core/tidy_warnings.php
+++ b/phpBB/includes/cron/tasks/core/tidy_warnings.php
@@ -16,7 +16,10 @@ if (!defined('IN_PHPBB'))
 	exit;
 }
 
-include_once($phpbb_root_path . 'includes/cron/cron_task_base.' . $phpEx);
+if (!class_exists('cron_task_base'))
+{
+	include($phpbb_root_path . 'includes/cron/cron_task_base.' . $phpEx);
+}
 
 /**
 * Tidy warnings cron task.
@@ -33,7 +36,10 @@ class cron_task_core_tidy_warnings extends cron_task_base
 	public function run()
 	{
 		global $phpbb_root_path, $phpEx;
-		include_once($phpbb_root_path . 'includes/functions_admin.' . $phpEx);
+		if (!function_exists('tidy_warnings'))
+		{
+			include($phpbb_root_path . 'includes/functions_admin.' . $phpEx);
+		}
 		tidy_warnings();
 	}