diff --git a/wp-includes/class-phpmailer.php b/wp-includes/class-phpmailer.php
index 25e5570a3..a533d1093 100644
--- a/wp-includes/class-phpmailer.php
+++ b/wp-includes/class-phpmailer.php
@@ -1402,6 +1402,15 @@ class PHPMailer {
     return trim($output);
   }
 
+  /**
+   * Callback for converting to "=XX".
+   * @access private
+   * @return string
+   */
+  function EncodeQ_callback ($matches) {
+    return "=".sprintf("%02X", ord($matches[1]));
+  }
+
   /**
    * Encode string to q encoding.
    * @access private
@@ -1413,15 +1422,18 @@ class PHPMailer {
 
     switch (strtolower($position)) {
       case 'phrase':
-        $encoded = preg_replace("/([^A-Za-z0-9!*+\/ -])/e", "'='.sprintf('%02X', ord('\\1'))", $encoded);
+        $encoded = preg_replace_callback("/([^A-Za-z0-9!*+\/ -])/",
+                                         "EncodeQ_callback", $encoded);
         break;
       case 'comment':
-        $encoded = preg_replace("/([\(\)\"])/e", "'='.sprintf('%02X', ord('\\1'))", $encoded);
+        $encoded = preg_replace_callback("/([\(\)\"])/",
+                                         "EncodeQ_callback", $encoded);
+        break;
       case 'text':
       default:
         /* Replace every high ascii, control =, ? and _ characters */
-        $encoded = preg_replace('/([\000-\011\013\014\016-\037\075\077\137\177-\377])/e',
-              "'='.sprintf('%02X', ord('\\1'))", $encoded);
+        $encoded = preg_replace_callback('/([\000-\011\013\014\016-\037\075\077\137\177-\377])/',
+                                         "EncodeQ_callback", $encoded);
         break;
     }
 
diff --git a/wp-includes/formatting.php b/wp-includes/formatting.php
index 153ef4e1f..145ee5ce2 100644
--- a/wp-includes/formatting.php
+++ b/wp-includes/formatting.php
@@ -772,6 +772,18 @@ function convert_chars($content, $deprecated = '') {
 	return $content;
 }
 
+/**
+ * Callback used to change %uXXXX to &#YYY; syntax
+ *
+ * @since 2.8?
+ *
+ * @param array $matches Single Match
+ * @return string An HTML entity
+ */
+function funky_javascript_callback($matches) {
+	return "&#".base_convert($matches[1],16,10).";";
+}
+
 /**
  * Fixes javascript bugs in browsers.
  *
@@ -788,9 +800,10 @@ function funky_javascript_fix($text) {
 	// Fixes for browsers' javascript bugs
 	global $is_macIE, $is_winIE;
 
-	/** @todo use preg_replace_callback() instead */
 	if ( $is_winIE || $is_macIE )
-		$text =  preg_replace("/\%u([0-9A-F]{4,4})/e",  "'&#'.base_convert('\\1',16,10).';'", $text);
+		$text =  preg_replace_callback("/\%u([0-9A-F]{4,4})/",
+					       "funky_javascript_callback",
+					       $text);
 
 	return $text;
 }