diff --git a/register_types.h b/register_types.h
index 546c2fb..c18c293 100644
--- a/register_types.h
+++ b/register_types.h
@@ -28,5 +28,10 @@
 /* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
 /*************************************************************************/
 
+#ifndef VISUAL_SCRIPT_REGISTER_TYPES_H
+#define VISUAL_SCRIPT_REGISTER_TYPES_H
+
 void register_visual_script_types();
 void unregister_visual_script_types();
+
+#endif // VISUAL_SCRIPT_REGISTER_TYPES_H