diff --git a/src/Form/Admin.php b/src/Form/Admin.php
index 9cfaa51..90febef 100644
--- a/src/Form/Admin.php
+++ b/src/Form/Admin.php
@@ -78,12 +78,17 @@ public function getFormId() {
   public function buildForm(array $form, FormStateInterface $form_state) {
     $config = $this->config('islandora_spreadsheet_ingest.settings');
     $current_whitelist = $config->get('binary_directory_whitelist');
+    $scheme_options = $this->streamWrapperManager->getNames(StreamWrapperInterface::READ_VISIBLE) + [
+      'http' => 'HTTP',
+      'https' => 'HTTPS',
+      'ftp' => 'FTP',
+    ];
     $form['schemes'] = [
       '#type' => 'checkboxes',
       '#title' => $this->t('Schemes'),
       '#description' => $this->t('Allowed list of schemes for which binaries can be referenced from.'),
       '#default_value' => $config->get('schemes') ?? [],
-      '#options' => $this->streamWrapperManager->getNames(StreamWrapperInterface::READ_VISIBLE),
+      '#options' => $scheme_options,
     ];
     $form['paths'] = [
       '#type' => 'textarea',
diff --git a/src/Plugin/migrate/process/AccessibleFile.php b/src/Plugin/migrate/process/AccessibleFile.php
index df155e8..97b10d6 100644
--- a/src/Plugin/migrate/process/AccessibleFile.php
+++ b/src/Plugin/migrate/process/AccessibleFile.php
@@ -6,8 +6,10 @@
 use Drupal\Core\File\FileSystemInterface;
 use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
 use Drupal\Core\StreamWrapper\StreamWrapperManagerInterface;
+use Drupal\Core\Url;
 use Drupal\migrate\MigrateExecutableInterface;
 use Drupal\migrate\MigrateSkipRowException;
+use Drupal\migrate\Plugin\MigrationInterface;
 use Drupal\migrate\ProcessPluginBase;
 use Drupal\migrate\Row;
 use Symfony\Component\DependencyInjection\ContainerInterface;
@@ -99,6 +101,20 @@ public function transform($value, MigrateExecutableInterface $migrate_executable
     $allowed_paths = $this->configFactory->get('islandora_spreadsheet_ingest.settings')->get('binary_directory_whitelist');
     $allowed_schemes = $this->configFactory->get('islandora_spreadsheet_ingest.settings')->get('schemes');
 
+    // Ignore this check if relevant configuration has not been set, and advise
+    // that the configuration should be set.
+    if (empty($allowed_paths) && empty($allowed_schemes)) {
+      $migrate_executable->saveMessage(
+        strtr("File access criteria is not defined; passing check of file (:file). For site security, it is highly recommended to set appropriate configuration at :config_url.", [
+          ':file' => $value,
+          ':config_url' => Url::fromRoute('islandora_spreadsheet_ingest.admin')->toString(),
+        ]),
+        MigrationInterface::MESSAGE_WARNING
+      );
+
+      return $value;
+    }
+
     // If it's a local path check to see if it's in our allowed list.
     $file_path = $this->fileSystem->realpath($value);
     if ($file_path) {