Index: wp-includes/functions-formatting.php
===================================================================
--- wp-includes/functions-formatting.php	(revision 3671)
+++ wp-includes/functions-formatting.php	(working copy)
@@ -41,7 +41,7 @@
 		} else {
 			$next = true;
 		}
-		$curl = preg_replace('/&([^#])(?![a-z1-4]{1,8};)/', '&$1', $curl);
+		$curl = preg_replace('/&([^#])(?![a-zA-Z1-4]{1,8};)/', '&$1', $curl);
 		$output .= $curl;
 	}
 	return $output;