diff --git a/parsecsv.lib.php b/parsecsv.lib.php
index 902903b..265ff22 100644
--- a/parsecsv.lib.php
+++ b/parsecsv.lib.php
@@ -6,6 +6,10 @@
 
 // Check if people used Composer to include this project in theirs
 if (!file_exists(__DIR__ . '/vendor/autoload.php')) {
+    require __DIR__ . '/src/enums/AbstractEnum.php';
+    require __DIR__ . '/src/enums/DatatypeEnum.php';
+    require __DIR__ . '/src/enums/FileProcessingModeEnum.php';
+    require __DIR__ . '/src/enums/SortEnum.php';
     require __DIR__ . '/src/extensions/DatatypeTrait.php';
     require __DIR__ . '/src/Csv.php';
 } else {