diff --git a/phpBB/phpbb/install/installer_configuration.php b/phpBB/phpbb/install/installer_configuration.php
index ab02da8686..c660c99d0f 100644
--- a/phpBB/phpbb/install/installer_configuration.php
+++ b/phpBB/phpbb/install/installer_configuration.php
@@ -93,6 +93,9 @@ class installer_configuration implements ConfigurationInterface
 						->scalarNode('smtp_host')
 							->defaultValue(null)
 							->end()
+						->scalarNode('smtp_port')
+							->defaultValue(null)
+							->end()
 						->scalarNode('smtp_auth')
 							->defaultValue(null)
 							->end()