diff --git a/src/Plugin/PdfBackend/PdftkPdfBackend.php b/src/Plugin/PdfBackend/PdftkPdfBackend.php
index 271d300fefb9db797c2c9e31e53f7c51950fa1c6..c46d61228d2afbb08d90040fcc424d966cd1d0a4 100644
--- a/src/Plugin/PdfBackend/PdftkPdfBackend.php
+++ b/src/Plugin/PdfBackend/PdftkPdfBackend.php
@@ -247,7 +247,7 @@ class PdftkPdfBackend extends PdfBackendBase implements ContainerFactoryPluginIn
     // Now feed this to pdftk and save the result to a variable.
     $pdftk_path = $this->getPdftkPath();
     ob_start();
-    $command = "{$pdftk_path} {$template_path} fill_form {$xfdf_path} output - " . ($context['flatten'] ? 'flatten ' : '') . "drop_xfa{$arg_pdftk_encryption}{$arg_permissions}{$arg_owner_password}{$arg_user_password}";
+    $command = "{$pdftk_path} {$template_path} fill_form {$xfdf_path} output - " . ($context['flatten'] ? 'flatten drop_xfa' : '') . "{$arg_pdftk_encryption}{$arg_permissions}{$arg_owner_password}{$arg_user_password}";
     passthru($command);
     $data = ob_get_clean();
     if ($data === FALSE) {