diff --git a/tests/phpunit/documentation/ReleaseNotesTest.php b/tests/phpunit/documentation/ReleaseNotesTest.php
index 05742d73ac5..d8d0fdc98c9 100644
--- a/tests/phpunit/documentation/ReleaseNotesTest.php
+++ b/tests/phpunit/documentation/ReleaseNotesTest.php
@@ -49,7 +49,8 @@ class ReleaseNotesTest extends MediaWikiTestCase {
 			"$type file '$fileName' is inaccessible."
 		);
 
-		foreach ( $file as $num => $line ) {
+		foreach ( $file as $i => $line ) {
+			$num = $i + 1;
 			$this->assertLessThanOrEqual(
 				// FILE_IGNORE_NEW_LINES drops the \n at the EOL, so max length is 80 not 81.
 				80,