Index: wp-includes/formatting.php
===================================================================
--- wp-includes/formatting.php	(revision 17424)
+++ wp-includes/formatting.php	(working copy)
@@ -2713,11 +2713,13 @@
  * @return string The excerpt.
  */
 function wp_html_excerpt( $str, $count ) {
-	$str = wp_strip_all_tags( $str, true );
-	$str = mb_substr( $str, 0, $count );
+	$new_str = wp_strip_all_tags( $str, true );
+	$new_str = mb_substr( $new_str, 0, $count );
 	// remove part of an entity at the end
-	$str = preg_replace( '/&[^;\s]{0,6}$/', '', $str );
-	return $str;
+	$new_str = preg_replace( '/&[^;\s]{0,6}$/', '', $new_str );
+	if( strlen( $new_str ) < strlen( $str ) )
+		$new_str .= '&hellip;';
+	return $new_str;
 }
 
 /**
@@ -2899,4 +2901,4 @@
 
 }
 
-?>
+?>
\ No newline at end of file