diff --git a/src/File/FileReader.php b/src/File/FileReader.php
index 90477570e3..5a0c5570fc 100644
--- a/src/File/FileReader.php
+++ b/src/File/FileReader.php
@@ -9,6 +9,9 @@ class FileReader
 
 	public static function read(string $fileName): string
 	{
+		if (!is_file($fileName)) {
+			throw new \PHPStan\File\CouldNotReadFileException($fileName);
+		}
 		$contents = @file_get_contents($fileName);
 		if ($contents === false) {
 			throw new \PHPStan\File\CouldNotReadFileException($fileName);