diff --git a/tests/console/thumbnail_test.php b/tests/console/thumbnail_test.php
index aa5e72bb82..68d4651757 100644
--- a/tests/console/thumbnail_test.php
+++ b/tests/console/thumbnail_test.php
@@ -97,11 +97,21 @@ class phpbb_console_command_thumbnail_test extends phpbb_database_test_case
 	{
 		parent::tearDown();
 
-		unlink($this->phpbb_root_path . 'files/test_png_1');
-		unlink($this->phpbb_root_path . 'files/test_png_2');
-		unlink($this->phpbb_root_path . 'files/test_txt');
-		unlink($this->phpbb_root_path . 'files/thumb_test_png_1');
-		unlink($this->phpbb_root_path . 'files/thumb_test_png_2');
+		$delete_files = [
+			$this->phpbb_root_path . 'files/test_png_1',
+			$this->phpbb_root_path . 'files/test_png_2',
+			$this->phpbb_root_path . 'files/test_txt',
+			$this->phpbb_root_path . 'files/thumb_test_png_1',
+			$this->phpbb_root_path . 'files/thumb_test_png_2'
+		];
+
+		foreach ($delete_files as $file)
+		{
+			if (file_exists($file))
+			{
+				unlink($file);
+			}
+		}
 	}
 
 	public function test_thumbnails()
diff --git a/tests/lint_test.php b/tests/lint_test.php
index 55fc394170..e7904f9c83 100644
--- a/tests/lint_test.php
+++ b/tests/lint_test.php
@@ -52,12 +52,12 @@ class lint_test extends phpbb_test_case
 		$this->assertEquals(0, $status, "PHP lint failed for $path:\n$output");
 	}
 
-	public function lint_data()
+	public static function lint_data(): array
 	{
-		return $this->check(__DIR__ . '/..');
+		return self::check(__DIR__ . '/..');
 	}
 
-	protected function check($root)
+	protected static function check($root): array
 	{
 		$files = array();
 		$dh = opendir($root);
@@ -92,7 +92,7 @@ class lint_test extends phpbb_test_case
 					__DIR__ . '/../node_modules',
 				)))
 			{
-				$files = array_merge($files, $this->check($path));
+				$files = array_merge($files, self::check($path));
 			}
 			else if (substr($filename, strlen($filename)-4) == '.php')
 			{