diff --git a/composer.json b/composer.json
index 5aad82909..a4e611cda 100644
--- a/composer.json
+++ b/composer.json
@@ -5,7 +5,7 @@
 	},
 	"scripts": {
 		"test": [
-			"parallel-lint . --exclude vendor --exclude includes/iterator/CallbackFilterIterator.php",
+			"parallel-lint . --exclude vendor",
 			"phpcs"
 		]
 	}
diff --git a/includes/iterator/CallbackFilterIterator.php b/includes/iterator/CallbackFilterIterator.php
index 4095d1d43..e4aa4a221 100644
--- a/includes/iterator/CallbackFilterIterator.php
+++ b/includes/iterator/CallbackFilterIterator.php
@@ -1,24 +1,27 @@
 <?php
 
-/**
- * This class is implemented as part of SPL starting at PHP5.4.  This
- * re-implementation provides backwards compatibility to mediawiki
- * running on PHP5.3.
- */
-class CallbackFilterIterator extends FilterIterator {
-	protected $callback;
+// T124828: conditional is a linter compatibility hack
+if ( !class_exists( 'CallbackFilterIterator' ) ) {
+	/**
+	 * This class is implemented as part of SPL starting at PHP5.4.  This
+	 * re-implementation provides backwards compatibility to mediawiki
+	 * running on PHP5.3.
+	 */
+	class CallbackFilterIterator extends FilterIterator {
+		protected $callback;
 
-	public function __construct( Iterator $iterator, $callback ) {
-		parent::__construct( $iterator );
-		$this->callback = $callback;
-	}
+		public function __construct( Iterator $iterator, $callback ) {
+			parent::__construct( $iterator );
+			$this->callback = $callback;
+		}
 
-	public function accept() {
-		return call_user_func(
-			$this->callback,
-			$this->current(),
-			$this->key(),
-			$this->getInnerIterator()
-		);
+		public function accept() {
+			return call_user_func(
+				$this->callback,
+				$this->current(),
+				$this->key(),
+				$this->getInnerIterator()
+			);
+		}
 	}
 }