diff --git a/docroot/includes/file.inc b/docroot/includes/file.inc
index 0ec69b7..86a84a5 100644
--- a/includes/file.inc
+++ b/includes/file.inc
@@ -1148,7 +1148,7 @@ function file_munge_filename($filename, $extensions, $alerts = TRUE) {
     // Remove any null bytes. See http://php.net/manual/security.filesystem.nullbytes.php
     $filename = str_replace(chr(0), '', $filename);
 
-    $whitelist = array_unique(explode(' ', trim($extensions)));
+    $whitelist = trim($extensions);
 
     // Split the filename up by periods. The first part becomes the basename
     // the last part the final extension.
@@ -1161,8 +1161,14 @@ function file_munge_filename($filename, $extensions, $alerts = TRUE) {
     // of allowed extensions.
     foreach ($filename_parts as $filename_part) {
       $new_filename .= '.' . $filename_part;
-      if (!in_array($filename_part, $whitelist) && preg_match("/^[a-zA-Z]{2,5}\d?$/", $filename_part)) {
-        $new_filename .= '_';
+
+      // Create a file object with the filename_part
+      $file = new stdClass();
+      $file->filename = '.' . $filename_part;
+
+      // Check if filename_part is allowed according to file_validate_extensions()
+      if (file_validate_extensions($file, $whitelist) !== array() && preg_match("/^[a-zA-Z]{2,5}\d?$/", $filename_part)) {
+         $new_filename .= '_';
       }
     }
     $filename = $new_filename . '.' . $final_extension;