diff --git a/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Configuration.php b/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Configuration.php
index b79bea6ad0..e78edaf356 100644
--- a/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Configuration.php
+++ b/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Configuration.php
@@ -244,7 +244,7 @@ class Configuration implements ConfigurationInterface
                         ->booleanNode('cookie_secure')->end()
                         ->booleanNode('cookie_httponly')->end()
                         ->scalarNode('gc_divisor')->end()
-                        ->scalarNode('gc_probability')->end()
+                        ->scalarNode('gc_probability')->defaultValue(1)->end()
                         ->scalarNode('gc_maxlifetime')->end()
                         ->scalarNode('save_path')->defaultValue('%kernel.cache_dir%/sessions')->end()
                         ->integerNode('metadata_update_threshold')