diff --git a/src/Streamer/FileCsv.php b/src/Streamer/FileCsv.php
index 59996cb..137bb3a 100644
--- a/src/Streamer/FileCsv.php
+++ b/src/Streamer/FileCsv.php
@@ -34,7 +34,7 @@ class FileCsv
     /** @var Log $log */
     private $log;
 
-    /** @var string $delimiter */
+    /** @var ?string $delimiter */
     private $delimiter;
 
     /** @var array $headers */
@@ -57,7 +57,7 @@ public function __construct(
         DirectoryList $directoryList,
         string $requestFile,
         Log $log,
-        string $delimiter,
+        ?string $delimiter = null,
         array $headers = [],
         string $escapeCharacter = ''
     ) {
diff --git a/src/Streamer/HttpCsv.php b/src/Streamer/HttpCsv.php
index 6739a50..5d69897 100644
--- a/src/Streamer/HttpCsv.php
+++ b/src/Streamer/HttpCsv.php
@@ -70,7 +70,7 @@ class HttpCsv
     private $log;
 
     /**
-     * @var string
+     * @var ?string
      */
     private $delimiter;
 
@@ -94,7 +94,7 @@ public function __construct(
         ConsoleOutput $consoleOutput,
         string $requestUrl,
         Log $log,
-        string $delimiter,
+        ?string $delimiter = null,
         string $encodingConversion = '',
         string $requestMethod = 'GET',
         array $requestOptions = [],