diff --git a/wp-includes/canonical.php b/wp-includes/canonical.php
index 0c56ba24f0..b19a245bd3 100644
--- a/wp-includes/canonical.php
+++ b/wp-includes/canonical.php
@@ -296,6 +296,7 @@ function redirect_canonical( $requested_url = null, $do_redirect = true ) {
 
 		if ( 'wp-register.php' == basename( $redirect['path'] ) ) {
 			if ( is_multisite() )
+				//duplicate_hook
 				$redirect_url = apply_filters( 'wp_signup_location', network_site_url( 'wp-signup.php' ) );
 			else
 				$redirect_url = site_url( 'wp-login.php?action=register' );
@@ -432,8 +433,17 @@ function redirect_canonical( $requested_url = null, $do_redirect = true ) {
 		$requested_url = preg_replace_callback('|%[a-fA-F0-9][a-fA-F0-9]|', 'lowercase_octets', $requested_url);
 	}
 
-	// Note that you can use the "redirect_canonical" filter to cancel a canonical redirect for whatever reason by returning false
-	$redirect_url = apply_filters('redirect_canonical', $redirect_url, $requested_url);
+	/**
+	 * Filter the canonical redirect URL.
+	 *
+	 * Returning false to this filter will cancel the redirect.
+	 *
+	 * @since 2.3.0
+	 *
+	 * @param string $redirect_url  The redirect URL.
+	 * @param string $requested_url The requested URL.
+	 */
+	$redirect_url = apply_filters( 'redirect_canonical', $redirect_url, $requested_url );
 
 	if ( !$redirect_url || $redirect_url == $requested_url ) // yes, again -- in case the filter aborted the request
 		return false;