diff --git a/src/Dev/CsvBulkLoader.php b/src/Dev/CsvBulkLoader.php
index fdfa5ef87..f9a90b6ff 100644
--- a/src/Dev/CsvBulkLoader.php
+++ b/src/Dev/CsvBulkLoader.php
@@ -169,7 +169,7 @@ class CsvBulkLoader extends BulkLoader
      */
     protected function getNewSplitFileName()
     {
-        return TEMP_FOLDER . '/' . uniqid('SilverStripe\\Dev\\BulkLoader', true) . '.csv';
+        return TEMP_FOLDER . DIRECTORY_SEPARATOR . uniqid(str_replace('\\', '_', static::class), true) . '.csv';
     }
 
     /**