diff --git a/mailsystem.module b/mailsystem.module
index e414280..8ec7018 100644
--- a/mailsystem.module
+++ b/mailsystem.module
@@ -181,11 +181,12 @@ class ' . $class_name . ' implements MailSystemInterface {';
     $file_condition = db_and()
       ->condition('filename', $class_file);
     db_delete('registry_file')
-      ->condition($file_condition);
+      ->condition($file_condition)
+      ->execute();
     db_delete('registry')->condition(
       db_or()->condition($class_condition)
       ->condition($file_condition)
-    );
+    )->execute();
     // Make sure that registry functions are available.
     require_once 'includes/registry.inc';
     // Parse the newly-created class file and add it to the registry.