diff --git a/src/wp-includes/default-filters.php b/src/wp-includes/default-filters.php
index 93fac65c7d..8d926e698e 100644
--- a/src/wp-includes/default-filters.php
+++ b/src/wp-includes/default-filters.php
@@ -87,6 +87,7 @@ add_filter( 'post_mime_type', 'sanitize_mime_type' );
 
 // Places to balance tags on input
 foreach ( array( 'content_save_pre', 'excerpt_save_pre', 'comment_save_pre', 'pre_comment_content' ) as $filter ) {
+	add_filter( $filter, 'convert_invalid_entities' );
 	add_filter( $filter, 'balanceTags', 50 );
 }
 
diff --git a/src/wp-includes/formatting.php b/src/wp-includes/formatting.php
index f255942b29..e295167e0e 100644
--- a/src/wp-includes/formatting.php
+++ b/src/wp-includes/formatting.php
@@ -1503,11 +1503,7 @@ function sanitize_html_class( $class, $fallback = '' ) {
 }
 
 /**
- * Converts a number of characters from a string.
- *
- * Metadata tags `<title>` and `<category>` are removed, `<br>` and `<hr>` are
- * converted into correct XHTML and Unicode characters are converted to the
- * valid range.
+ * Converts lone & characters into `&#038;` (a.k.a. `&amp;`)
  *
  * @since 0.71
  *
@@ -1516,58 +1512,64 @@ function sanitize_html_class( $class, $fallback = '' ) {
  * @return string Converted string.
  */
 function convert_chars( $content, $deprecated = '' ) {
-	if ( !empty( $deprecated ) )
+	if ( ! empty( $deprecated ) ) {
 		_deprecated_argument( __FUNCTION__, '0.71' );
+	}
 
-	// Translation of invalid Unicode references range to valid range
+	if ( strpos( $content, '&' ) !== false ) {
+		$content = preg_replace( '/&([^#])(?![a-z1-4]{1,8};)/i', '&#038;$1', $content );
+	}
+
+	return $content;
+}
+
+/**
+ * Converts invalid Unicode references range to valid range.
+ *
+ * @since 4.3
+ *
+ * @param string $content String with entities that need converting.
+ * @return string Converted string.
+ */
+function convert_invalid_entities( $content ) {
 	$wp_htmltranswinuni = array(
-	'&#128;' => '&#8364;', // the Euro sign
-	'&#129;' => '',
-	'&#130;' => '&#8218;', // these are Windows CP1252 specific characters
-	'&#131;' => '&#402;',  // they would look weird on non-Windows browsers
-	'&#132;' => '&#8222;',
-	'&#133;' => '&#8230;',
-	'&#134;' => '&#8224;',
-	'&#135;' => '&#8225;',
-	'&#136;' => '&#710;',
-	'&#137;' => '&#8240;',
-	'&#138;' => '&#352;',
-	'&#139;' => '&#8249;',
-	'&#140;' => '&#338;',
-	'&#141;' => '',
-	'&#142;' => '&#381;',
-	'&#143;' => '',
-	'&#144;' => '',
-	'&#145;' => '&#8216;',
-	'&#146;' => '&#8217;',
-	'&#147;' => '&#8220;',
-	'&#148;' => '&#8221;',
-	'&#149;' => '&#8226;',
-	'&#150;' => '&#8211;',
-	'&#151;' => '&#8212;',
-	'&#152;' => '&#732;',
-	'&#153;' => '&#8482;',
-	'&#154;' => '&#353;',
-	'&#155;' => '&#8250;',
-	'&#156;' => '&#339;',
-	'&#157;' => '',
-	'&#158;' => '&#382;',
-	'&#159;' => '&#376;'
+		'&#128;' => '&#8364;', // the Euro sign
+		'&#129;' => '',
+		'&#130;' => '&#8218;', // these are Windows CP1252 specific characters
+		'&#131;' => '&#402;',  // they would look weird on non-Windows browsers
+		'&#132;' => '&#8222;',
+		'&#133;' => '&#8230;',
+		'&#134;' => '&#8224;',
+		'&#135;' => '&#8225;',
+		'&#136;' => '&#710;',
+		'&#137;' => '&#8240;',
+		'&#138;' => '&#352;',
+		'&#139;' => '&#8249;',
+		'&#140;' => '&#338;',
+		'&#141;' => '',
+		'&#142;' => '&#381;',
+		'&#143;' => '',
+		'&#144;' => '',
+		'&#145;' => '&#8216;',
+		'&#146;' => '&#8217;',
+		'&#147;' => '&#8220;',
+		'&#148;' => '&#8221;',
+		'&#149;' => '&#8226;',
+		'&#150;' => '&#8211;',
+		'&#151;' => '&#8212;',
+		'&#152;' => '&#732;',
+		'&#153;' => '&#8482;',
+		'&#154;' => '&#353;',
+		'&#155;' => '&#8250;',
+		'&#156;' => '&#339;',
+		'&#157;' => '',
+		'&#158;' => '&#382;',
+		'&#159;' => '&#376;'
 	);
 
-	// Remove metadata tags
-	$content = preg_replace('/<title>(.+?)<\/title>/','',$content);
-	$content = preg_replace('/<category>(.+?)<\/category>/','',$content);
-
-	// Converts lone & characters into &#38; (a.k.a. &amp;)
-	$content = preg_replace('/&([^#])(?![a-z1-4]{1,8};)/i', '&#038;$1', $content);
-
-	// Fix Word pasting
-	$content = strtr($content, $wp_htmltranswinuni);
-
-	// Just a little XHTML help
-	$content = str_replace('<br>', '<br />', $content);
-	$content = str_replace('<hr>', '<hr />', $content);
+	if ( strpos( $content, '&#1' ) !== false ) {
+		$content = strtr( $content, $wp_htmltranswinuni );
+	}
 
 	return $content;
 }