diff --git a/install_minimal/DoctrineMigrations/Version20110711161043.php b/install_minimal/DoctrineMigrations/Version20110711161043.php
index ea2705db7..4a0bed554 100644
--- a/install_minimal/DoctrineMigrations/Version20110711161043.php
+++ b/install_minimal/DoctrineMigrations/Version20110711161043.php
@@ -24,7 +24,7 @@ class Version20110711161043 extends AbstractMigration
 
         /* 2) create a foreign key relationship from cc_files to cc_music_dirs */
         $cc_files = $schema->getTable('cc_files');
-        $cc_files->addColumn('directory', 'integer', array('default'=> NULL));
+        $cc_files->addColumn('directory', 'integer', array('notnull' => 0, 'default'=> NULL));
 
         $cc_files->addNamedForeignKeyConstraint('cc_music_dirs_folder_fkey', $cc_music_dirs, array('directory'), array('id'), array('onDelete' => 'CASCADE'));