diff --git a/weight.install b/weight.install
index 34293a3..68a3521 100644
--- a/weight.install
+++ b/weight.install
@@ -72,15 +72,36 @@ function weight_update_7300() {
       }
     }
   }
-
-  $_SESSION['weight_field_name'] = $field_name;
 }
 
 /**
  * Migrate weights to Weight field.
  */
 function weight_update_7301(&$sandbox) {
-  $field_name = $_SESSION['weight_field_name'];
+  static $field_name = NULL;
+  if (!$field_name) {
+    $fields = field_read_fields(array('type' => 'weight'));
+    $field_name = key($fields);
+    $field = $fields[$field_name];
+
+    if ($field['storage']['type'] == 'field_sql_storage') {
+      $sql = <<<SQL
+INSERT INTO field_data_{$field_name}
+SELECT 'node', type as bundle, 0 as deleted, entity_id, vid as revision_id, 'und' as language, 0 as delta, weight as {$field_name}_value
+FROM weight_weights
+  INNER JOIN node ON nid=entity_id
+SQL;
+      db_query($sql);
+      $sql = <<<SQL
+INSERT INTO field_revision_{$field_name}
+SELECT 'node', type as bundle, 0 as deleted, entity_id, vid as revision_id, 'und' as language, 0 as delta, weight as {$field_name}_value
+FROM weight_weights
+  INNER JOIN node ON nid=entity_id
+SQL;
+      db_query($sql);
+      return;
+    }
+  }
 
   // Check for weight_weights table.
   if (db_table_exists('weight_weights')) {