diff --git a/includes/unicode.inc b/includes/unicode.inc
index 80ea87714465c4ddcaceb36d5062f8e6717af69b..04751ed79988bc49c941f41ec616ec6670f57737 100644
--- a/includes/unicode.inc
+++ b/includes/unicode.inc
@@ -258,31 +258,6 @@ function _mime_header_decode($matches) {
   return $data;
 }
 
-/**
- * Complement to mime_header_encode
- */
-function mime_header_decode($header) {
-  // First step: encoded chunks followed by other encoded chunks (need to collapse whitespace)
-  $header = preg_replace_callback('/=\?([^?]+)\?(Q|B)\?([^?]+|\?(?!=))\?=\s+(?==\?)/', '_mime_header_decode', $header);
-  // Second step: remaining chunks (do not collapse whitespace)
-  return preg_replace_callback('/=\?([^?]+)\?(Q|B)\?([^?]+|\?(?!=))\?=/', '_mime_header_decode', $header);
-}
-
-/**
- * Helper function to mime_header_decode
- */
-function _mime_header_decode($matches) {
-  // Regexp groups:
-  // 1: Character set name
-  // 2: Escaping method (Q or B)
-  // 3: Encoded data
-  $data = ($matches[2] == 'B') ? base64_decode($matches[3]) : str_replace('_', ' ', quoted_printable_decode($matches[3]));
-  if (strtolower($matches[1]) != 'utf-8') {
-    $data = drupal_convert_to_utf8($data, $matches[1]);
-  }
-  return $data;
-}
-
 /**
  * Decode all HTML entities (including numerical ones) to regular UTF-8 bytes.
  * Double-escaped entities will only be decoded once ("&amp;lt;" becomes "&lt;", not "<").