Index: wp-admin/includes/user.php
===================================================================
--- wp-admin/includes/user.php	(revision 17420)
+++ wp-admin/includes/user.php	(working copy)
@@ -686,7 +686,7 @@
 
 		if ( $this->role ) {
 			$this->query_from .= " INNER JOIN $wpdb->usermeta ON $wpdb->users.ID = $wpdb->usermeta.user_id";
-			$this->query_where .= $wpdb->prepare(" AND $wpdb->usermeta.meta_key = '{$wpdb->prefix}capabilities' AND $wpdb->usermeta.meta_value LIKE %s", '%' . $this->role . '%');
+			$this->query_where .= $wpdb->prepare(" AND $wpdb->usermeta.meta_key = '{$wpdb->prefix}capabilities' AND $wpdb->usermeta.meta_value LIKE %s", '%"' . $this->role . '"%');
 		} elseif ( is_multisite() ) {
 			$level_key = $wpdb->prefix . 'capabilities'; // wpmu site admins don't have user_levels
 			$this->query_from .= ", $wpdb->usermeta";
Index: wp-includes/user.php
===================================================================
--- wp-includes/user.php	(revision 17420)
+++ wp-includes/user.php	(working copy)
@@ -456,7 +456,7 @@
 		// Build a CPU-intensive query that will return concise information.
 		$select_count = array();
 		foreach ( $avail_roles as $this_role => $name ) {
-			$select_count[] = "COUNT(NULLIF(`meta_value` LIKE '%" . like_escape($this_role) . "%', FALSE))";
+			$select_count[] = "COUNT(NULLIF(`meta_value` LIKE '%\"" . like_escape($this_role) . "\"%', FALSE))";
 		}
 		$select_count = implode(', ', $select_count);