diff --git a/mollom.install b/mollom.install
index 29d8a7b..2c3a0c4 100644
--- a/mollom.install
+++ b/mollom.install
@@ -199,7 +199,7 @@ function mollom_schema() {
         'description' => 'A special reason for why a post was blocked.',
         'type' => 'varchar',
         'length' => 255,
-        'not null' => TRUE,
+        'not null' => FALSE,
         'default' => '',
       ),
       'languages' => array(