diff -u b/cas.install b/cas.install
--- b/cas.install
+++ b/cas.install
@@ -390,8 +390,7 @@
 /**
  * Add session ID to cas login data table.
  */
-function cas_update_7101() {
-  db_drop_field('cas_login_data', 'sid');
+function cas_update_7103() {
   db_add_field('cas_login_data', 'sid', array('type' => 'varchar', 'length' => 128, 'not null' => TRUE, 'default' => 0));
 
   // log everyone out so that things don't get oddly out of sync