diff --git a/phpBB/includes/functions.php b/phpBB/includes/functions.php
index 1a3560dbb1..56363ed5c0 100644
--- a/phpBB/includes/functions.php
+++ b/phpBB/includes/functions.php
@@ -2397,7 +2397,8 @@ function build_url($strip_vars = false)
 	global $config, $user, $phpbb_path_helper;
 
 	$php_ext = $phpbb_path_helper->get_php_ext();
-	$page = $user->page['page'];
+	// Change page back to expected format
+	$page = str_replace('&', '&', urldecode($user->page['page']));
 
 	// We need to be cautious here.
 	// On some situations, the redirect path is an absolute URL, sometimes a relative path
diff --git a/tests/functions/build_url_test.php b/tests/functions/build_url_test.php
index 06415a424e..df178f277e 100644
--- a/tests/functions/build_url_test.php
+++ b/tests/functions/build_url_test.php
@@ -79,9 +79,16 @@ class phpbb_build_url_test extends phpbb_test_case
 	{
 		global $user, $phpbb_root_path;
 
-		$user->page['page'] = $page;
+		$user->page['page'] = str_replace('%2F', '/', urlencode($this->sanitizer($page)));
 		$output = build_url($strip_vars);
 
 		$this->assertEquals($expected, $output);
 	}
+
+	protected function sanitizer($value)
+	{
+		$type_cast_helper = new \phpbb\request\type_cast_helper();
+		$type_cast_helper->set_var($value, $value, gettype($value), true);
+		return $value;
+	}
 }