diff --git a/src/core/core.hpp b/src/core/core.hpp
index 782ee384..5f803ee1 100644
--- a/src/core/core.hpp
+++ b/src/core/core.hpp
@@ -5,6 +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 once
 
 #include "gfx.hpp"
 
diff --git a/src/core/gfx.hpp b/src/core/gfx.hpp
index 0165855f..157680a3 100644
--- a/src/core/gfx.hpp
+++ b/src/core/gfx.hpp
@@ -5,6 +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 once
 
 #include <ox/std/types.hpp>