Index: wp-includes/link-template.php
===================================================================
--- wp-includes/link-template.php	(revision 19727)
+++ wp-includes/link-template.php	(working copy)
@@ -1565,7 +1565,7 @@
 
 	if ( !is_single() && $paged > 1 ) {
 		$attr = apply_filters( 'previous_posts_link_attributes', '' );
-		return '<a href="' . previous_posts( false ) . "\" $attr>". preg_replace( '/&([^#])(?![a-z]{1,8};)/', '&#038;$1', $label ) .'</a>';
+		return '<a href="' . previous_posts( false ) . "\" $attr>". preg_replace( '/&([^#])(?![a-z]{1,8};)/i', '&#038;$1', $label ) .'</a>';
 	}
 }