diff --git a/db/migrate/20190724055909_move_to_managed_authenticator.rb b/db/migrate/20190724055909_move_to_managed_authenticator.rb
index 6356bc1..09cc1d4 100644
--- a/db/migrate/20190724055909_move_to_managed_authenticator.rb
+++ b/db/migrate/20190724055909_move_to_managed_authenticator.rb
@@ -17,6 +17,7 @@ class MoveToManagedAuthenticator < ActiveRecord::Migration[5.2]
       CURRENT_TIMESTAMP
     FROM plugin_store_rows
     WHERE plugin_name = 'oauth2_basic'
+    AND value::json->>'user_id' ~ '^[0-9]+$'
     ON CONFLICT (provider_name, user_id)
     DO NOTHING
     SQL