diff --git a/phpBB/docs/CHANGELOG.html b/phpBB/docs/CHANGELOG.html
index 5c627ae16c..eee01525aa 100644
--- a/phpBB/docs/CHANGELOG.html
+++ b/phpBB/docs/CHANGELOG.html
@@ -185,6 +185,7 @@
 		<li>[Fix] Correctly log action when users request to join a group (Bug #37585 - Patch by nickvergessen)</li>
 		<li>[Fix] Do not try to create thumbnails for images we cannot open properly. (Bug #48695)</li>
 		<li>[Fix] Apply locale-independent basename() to attachment filenames. New function added: utf8_basename(). (Bug #43335 - Patch by ocean=Yohsuke)</li>
+		<li>[Fix] Adjust build_url() to not prepend $phpbb_root_path if path returned from redirect() is an URL. This fixes redirect issues with some installations and bridges. (Bug #47535)</li>
 		<li>[Change] Change the data format of the default file ACM to be more secure from tampering and have better performance.</li>
 		<li>[Change] Add index on log_time to the log table to prevent slowdown on boards with many log entries. (Bug #44665 - Patch by bantu)</li>
 		<li>[Change] Template engine now permits to a limited extent variable includes.</li>
diff --git a/phpBB/includes/functions.php b/phpBB/includes/functions.php
index 241bed408f..d147872c34 100644
--- a/phpBB/includes/functions.php
+++ b/phpBB/includes/functions.php
@@ -2284,7 +2284,7 @@ function redirect($url, $return = false, $disable_cd_check = false)
 	$url = str_replace('&amp;', '&', $url);
 
 	// Determine which type of redirect we need to handle...
-	$url_parts = parse_url($url);
+	$url_parts = @parse_url($url);
 
 	if ($url_parts === false)
 	{
@@ -2497,6 +2497,18 @@ function build_url($strip_vars = false)
 		$redirect .= ($query) ? '?' . $query : '';
 	}
 
+	// We need to be cautious here.
+	// On some situations, the redirect path is an absolute URL, sometimes a relative path
+	// For a relative path, let's prefix it with $phpbb_root_path to point to the correct location,
+	// else we use the URL directly.
+	$url_parts = @parse_url($redirect);
+
+	// URL
+	if ($url_parts !== false && !empty($url_parts['scheme']) && !empty($url_parts['host']))
+	{
+		return str_replace('&', '&amp;', $redirect);
+	}
+
 	return $phpbb_root_path . str_replace('&', '&amp;', $redirect);
 }
 
@@ -3596,7 +3608,7 @@ function msg_handler($errno, $msg_text, $errfile, $errline)
 
 			exit_handler();
 		break;
-		
+
 		// PHP4 comptibility
 		case E_DEPRECATED:
 			return true;