diff --git a/src/wp-includes/pluggable.php b/src/wp-includes/pluggable.php
index da637ebbcfefc..5cdcc87288b52 100644
--- a/src/wp-includes/pluggable.php
+++ b/src/wp-includes/pluggable.php
@@ -710,7 +710,7 @@ function wp_validate_auth_cookie( $cookie = '', $scheme = '' ) {
 		$username   = $cookie_elements['username'];
 		$hmac       = $cookie_elements['hmac'];
 		$token      = $cookie_elements['token'];
-		$expired    = $cookie_elements['expiration'];
+		$expired    = (int) $cookie_elements['expiration'];
 		$expiration = $cookie_elements['expiration'];
 
 		// Allow a grace period for POST and Ajax requests.