diff --git a/src/_types.hpp b/src/_types.hpp
index bf1e89cfe..c28b0ed1c 100644
--- a/src/_types.hpp
+++ b/src/_types.hpp
@@ -5,7 +5,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
  */
-#pragma
+#pragma once
 
 #define offsetof(st, m) ((size_t)(&((st *)0)->m))