diff --git a/cck.install b/cck.install
index 49a2f9b2c..aad9102d9 100644
--- a/cck.install
+++ b/cck.install
@@ -24,6 +24,12 @@ function cck_schema() {
 
   $schema['cck_field_settings'] = array(
     'fields' => array(
+     'id' => array(
+       'description' => 'The unique identifier for field settings.',
+       'type' => 'serial',
+       'unsigned' => TRUE,
+       'not null' => TRUE,
+      ),
       'field_name' => array(
         'type' => 'varchar',
         'length' => 32,
@@ -68,6 +74,7 @@ function cck_schema() {
         'description' => 'The custom value for this setting.',
       ),
     ),
+    'primary key' => array('id'),
   );
   return $schema;
 }
@@ -93,3 +100,19 @@ function cck_update_7000() {
     db_add_field('cck_field_settings', 'language', $field);
   }
 }
+
+/**
+ * Add a primary key.
+ */
+function cck_update_7001() {
+  if (!db_field_exists('cck_field_settings', 'id')) {
+    db_add_field('cck_field_settings', 'id',
+      array(
+        'description' => 'The unique identifier for field settings.',
+        'type' => 'serial',
+        'unsigned' => TRUE,
+        'not null' => TRUE,
+      ),
+      array('primary key' => array('id')));
+  }
+}